Article Over Grading of Blue Fluorescent Diamonds Revisited

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael, as I read your paper I have a couple more questions for you. I am personally more experienced with reading medical journals (more specifically pharmaceutical research) and am accustomed to finding the "limitations" section at the end. I am curious as to whether you formulated a list of limitations and what that list may look like?

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?
What sort of master set of stones did you use for your grading of these 25 stones?
Was the selection of diamonds to be used done at random and why only 25 stones?
Were the specified light sources the ONLY source of light in the room at the time of grading?

I hope you don't take these questions as an indication of me trying to poke holes in your study. They are very real questions I would like to know in order to evaluate the study. I happen to come into this discussion feeling like a UV filter should be used for diamond grading and don't see why the use of a filter would be detrimental to the consumer. If UV light is causing a chameleon effect on stones that is dependent upon the lighting it should be eliminated as a variable, especially considering that we don't know why certain fluorescing stones behave one way and others seem to behave another way.

This post by pfunk encompasses most all questions asked about my color grading methodology, limitations and skill asked over many pages by everyone including Sharon, Garry, David and Karl. So this response is to and for everyone who asked.

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?

Credentials and training in diamond grading are a subset of gemology credentials. In the US there are two main avenues to a credential in gemology. One is the Diploma Course and examination to obtain the designation FGA (Fellow of the Gemmological Association of Great Britain). The other is the more widely held (in the US) Diploma course and examination to obtain the credential GG ( Graduate Gemologist) at GIA. It is generally acknowledged in the appraisal community that the FGA program is more academically rigorous and challenging, but in the field of diamond grading GIA is the acknowledged leader and their diamond course superior.

My gemology diploma is FGA, and I own and have researched all four generations of GIA Graduate Gemologist courses from the 60's to the present. I hold the certification by the Accredited Gemologist Association, Certified Gemological Laboratory(CGL) and am a Senior Member of that Association. Senior Member status with the National Association of Jewelry Appraisers was attained after years of continuing education in the fields of gemology and appraising.

What sort of master set of stones did you use for your grading of these 25 stones?

I employed my 10 stone set of quarter carat to three-eighth carat masters built during the 80's by sending stones to GIA where their top color grader (now retired) Karen Hurwit graded them as Masters. I also had access to and employed what I believe for several reasons to be the best 10 stone master set Karen ever put together. That set of Lazar Kaplin Ideal cut diamond masters was made for diamond dealer and CZ master manufacturer Barry Ellin. Here is a photo of that master stone set of nine, whole-grade master diamonds from E to L and N from my article "A place for CZ masters in diamond colour grading" in the Journal of Gemmology / 2008 / Volume 31 / No. 3/4.


For those interested in greater depth of understanding of color grading this article:
( http://acagemlab.com/temp/CowingCZ.pdf ) goes way beyond a "Consumer's Report" style evaluation of the two major CZ master sets available and widely in use in the US.

Findings are reported of studies in five areas related to diamond color grading:

1. The historical development by the Gemological Institute of America (GIA) of a color grading standard beginning with the GIA color grading ‘yardstick’.

2. Industry and GIA teaching of methods and recommendations for color grading using GIA Diamond Masters, which reduce the subjectivity of color grading.

3. The pros and cons in the use of CZ master stones in diamond color grading.

4. A study of grading light environments using five lighting types that resulted in additional recommendations for color grading using diamond or CZ master stones.

Was the selection of diamonds to be used done at random and why only 25 stones?

For the Medium, Strong and Very Strong Blues, the 25 diamond database was made up of the first five stones of each strength having post-2000 GIA grading reports that I was able to obtain. The faint and none used as a control were likewise randomly obtained, most with GIA grading reports. Antoinette Matlins happened fortuitously to have the VST Blue cushion #5 that turned out to be the true blue-white top color diamond historically called Jager.

Were the specified light sources the ONLY source of light in the room at the time of grading?

Grading was done in each light in an otherwise relatively dark room.

Finally, remember the grading in GIA DiamondDock standard lighting is by GIA GTL, and AGSL as well as me. As Bryan has pointed out, all three agree within tolerance on the grades of the study's 10 non-fluoresent control diamonds. This close correlation in grading supports the grading skill and consistency of all three. It is only as the strength of the diamond's fluorescence goes from medium to strong to very strong blue that differences and inconsistencies arise and worsen.

Michael, thanks for posting this- but haven't we moved past the point in the discussion regarding GIA and systematic overgrading of MB/SB stones?
It's not happening and there's been no credible evidence shown to substantiate the claim.

Let's agree you saw a stone as a J color that GIA saw as a G and AGSL saw as an H.
Maybe it was an anomaly. Maybe the methods you used produced an errant result- but it's important to make sure this part is clear.
It's possible to find errors in GIA grades- but they are quite rare and indicate no systematic problem

Carefull, the ghosts of Frank Wade and GIA founder Robert Shipley as well as past GIA graduate gemologistare are likely to rise out of their graves and haunt you repeating over and over again " Fluorescent diamonds should be graded at their color in artificial light devoid of ultraviolet radiation, rather than at their daylight appearance."

Remember, the overgrading and inconsistency problem that is clearly documented in the 2010 Study remains even after the GIA switched to the DiamondDock, and was reinforced by studies in Israel by Tom Tashey and the World Gemological Institute (WGI), an international diamond grading and research center of the Israel Diamond Institute (IDI).

Using the DiamondDock with and without UV filter, he and the Israeli graders did not find much difference or improvement from the DiamondLite to the DiamondDock. They found less improvement than the 2010 study's finding of reduction in overgrading from four grades of fluorescence enhancement in the DiamondLite to two grades in the DiamondDock in 3 of the 5 VST Blues.

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael, as I read your paper I have a couple more questions for you. I am personally more experienced with reading medical journals (more specifically pharmaceutical research) and am accustomed to finding the "limitations" section at the end. I am curious as to whether you formulated a list of limitations and what that list may look like?

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?
What sort of master set of stones did you use for your grading of these 25 stones?
Was the selection of diamonds to be used done at random and why only 25 stones?
Were the specified light sources the ONLY source of light in the room at the time of grading?

I hope you don't take these questions as an indication of me trying to poke holes in your study. They are very real questions I would like to know in order to evaluate the study. I happen to come into this discussion feeling like a UV filter should be used for diamond grading and don't see why the use of a filter would be detrimental to the consumer. If UV light is causing a chameleon effect on stones that is dependent upon the lighting it should be eliminated as a variable, especially considering that we don't know why certain fluorescing stones behave one way and others seem to behave another way.

This post by pfunk encompasses most all questions asked about my color grading methodology, limitations and skill asked over many pages by everyone including Sharon, Garry, David and Karl. So this response is to and for everyone who asked.

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?

Credentials and training in diamond grading are a subset of gemology credentials. In the US there are two main avenues to a credential in gemology. One is the Diploma Course and examination to obtain the designation FGA (Fellow of the Gemmological Association of Great Britain). The other is the more widely held (in the US) Diploma course and examination to obtain the credential GG ( Graduate Gemologist) at GIA. It is generally acknowledged in the appraisal community that the FGA program is more academically rigorous and challenging, but in the field of diamond grading GIA is the acknowledged leader and their diamond course superior.

My gemology diploma is FGA, and I own and have researched all four generations of GIA Graduate Gemologist courses from the 60's to the present. I hold the certification by the Accredited Gemologist Association, Certified Gemological Laboratory(CGL) and am a Senior Member of that Association. Senior Member status with the National Association of Jewelry Appraisers was attained after years of continuing education in the fields of gemology and appraising.

What sort of master set of stones did you use for your grading of these 25 stones?

I employed my 10 stone set of quarter carat to three-eighth carat masters built during the 80's by sending stones to GIA where their top color grader (now retired) Karen Hurwit graded them as Masters. I also had access to and employed what I believe for several reasons to be the best 10 stone master set Karen ever put together. That set of Lazar Kaplin Ideal cut diamond masters was made for diamond dealer and CZ master manufacturer Barry Ellin. Here is a photo of that master stone set of nine, whole-grade master diamonds from E to L and N from my article "A place for CZ masters in diamond colour grading" in the Journal of Gemmology / 2008 / Volume 31 / No. 3/4.


For those interested in greater depth of understanding of color grading this article:
( http://acagemlab.com/temp/CowingCZ.pdf ) goes way beyond a "Consumer's Report" style evaluation of the two major CZ master sets available and widely in use in the US.

Findings are reported of studies in five areas related to diamond color grading:

1. The historical development by the Gemological Institute of America (GIA) of a color grading standard beginning with the GIA color grading ‘yardstick’.

2. Industry and GIA teaching of methods and recommendations for color grading using GIA Diamond Masters, which reduce the subjectivity of color grading.

3. The pros and cons in the use of CZ master stones in diamond color grading.

4. A study of grading light environments using five lighting types that resulted in additional recommendations for color grading using diamond or CZ master stones.

Was the selection of diamonds to be used done at random and why only 25 stones?

For the Medium, Strong and Very Strong Blues, the 25 diamond database was made up of the first five stones of each strength having post-2000 GIA grading reports that I was able to obtain. The faint and none used as a control were likewise randomly obtained, most with GIA grading reports. Antoinette Matlins happened fortuitously to have the VST Blue cushion #5 that turned out to be the true blue-white top color diamond historically called Jager.

Were the specified light sources the ONLY source of light in the room at the time of grading?

Grading was done in each light in an otherwise relatively dark room.

Finally, remember the grading in GIA DiamondDock standard lighting is by GIA GTL, and AGSL as well as me. As Bryan has pointed out, all three agree within tolerance on the grades of the study's 10 non-fluoresent control diamonds. This close correlation in grading supports the grading skill and consistency of all three. It is only as the strength of the diamond's fluorescence goes from medium to strong to very strong blue that differences and inconsistencies arise and worsen.

Michael, thanks for posting this- but haven't we moved past the point in the discussion regarding GIA and systematic overgrading of MB/SB stones?
It's not happening and there's been no credible evidence shown to substantiate the claim.

Let's agree you saw a stone as a J color that GIA saw as a G and AGSL saw as an H.
Maybe it was an anomaly. Maybe the methods you used produced an errant result- but it's important to make sure this part is clear.
It's possible to find errors in GIA grades- but they are quite rare and indicate no systematic problem

Careful, the spirits of Frank Wade and GIA founder Robert Shipley as well as past GIA graduate gemologists are likely to rise out of their graves and haunt you repeating over and over again "Fluorescent diamonds should be graded at their color in artificial light devoid of ultraviolet radiation, rather than at their daylight appearance."

Remember, the overgrading and inconsistency problem that is clearly documented in the 2010 Study remains even after the GIA switched to the DiamondDock, and was reinforced by studies in Israel by Tom Tashey and the World Gemological Institute (WGI), an international diamond grading and research center of the Israel Diamond Institute (IDI).

Using the DiamondDock with and without UV filter, Tashey and the Israeli graders did not find much difference or improvement from the DiamondLite to the DiamondDock. They found less improvement than the 2010 study's finding of reduction in overgrading from four grades of fluorescence enhancement in the DiamondLite to two grades in the DiamondDock in 3 of the 5 VST Blues.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael, as I read your paper I have a couple more questions for you. I am personally more experienced with reading medical journals (more specifically pharmaceutical research) and am accustomed to finding the "limitations" section at the end. I am curious as to whether you formulated a list of limitations and what that list may look like?

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?
What sort of master set of stones did you use for your grading of these 25 stones?
Was the selection of diamonds to be used done at random and why only 25 stones?
Were the specified light sources the ONLY source of light in the room at the time of grading?

I hope you don't take these questions as an indication of me trying to poke holes in your study. They are very real questions I would like to know in order to evaluate the study. I happen to come into this discussion feeling like a UV filter should be used for diamond grading and don't see why the use of a filter would be detrimental to the consumer. If UV light is causing a chameleon effect on stones that is dependent upon the lighting it should be eliminated as a variable, especially considering that we don't know why certain fluorescing stones behave one way and others seem to behave another way.

This post by pfunk encompasses most all questions asked about my color grading methodology, limitations and skill asked over many pages by everyone including Sharon, Garry, David and Karl. So this response is to and for everyone who asked.

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?

Credentials and training in diamond grading are a subset of gemology credentials. In the US there are two main avenues to a credential in gemology. One is the Diploma Course and examination to obtain the designation FGA (Fellow of the Gemmological Association of Great Britain). The other is the more widely held (in the US) Diploma course and examination to obtain the credential GG ( Graduate Gemologist) at GIA. It is generally acknowledged in the appraisal community that the FGA program is more academically rigorous and challenging, but in the field of diamond grading GIA is the acknowledged leader and their diamond course superior.

My gemology diploma is FGA, and I own and have researched all four generations of GIA Graduate Gemologist courses from the 60's to the present. I hold the certification by the Accredited Gemologist Association, Certified Gemological Laboratory(CGL) and am a Senior Member of that Association. Senior Member status with the National Association of Jewelry Appraisers was attained after years of continuing education in the fields of gemology and appraising.

What sort of master set of stones did you use for your grading of these 25 stones?

I employed my 10 stone set of quarter carat to three-eighth carat masters built during the 80's by sending stones to GIA where their top color grader (now retired) Karen Hurwit graded them as Masters. I also had access to and employed what I believe for several reasons to be the best 10 stone master set Karen ever put together. That set of Lazar Kaplin Ideal cut diamond masters was made for diamond dealer and CZ master manufacturer Barry Ellin. Here is a photo of that master stone set of nine, whole-grade master diamonds from E to L and N from my article "A place for CZ masters in diamond colour grading" in the Journal of Gemmology / 2008 / Volume 31 / No. 3/4.


For those interested in greater depth of understanding of color grading this article:
( http://acagemlab.com/temp/CowingCZ.pdf ) goes way beyond a "Consumer's Report" style evaluation of the two major CZ master sets available and widely in use in the US.

Findings are reported of studies in five areas related to diamond color grading:

1. The historical development by the Gemological Institute of America (GIA) of a color grading standard beginning with the GIA color grading ‘yardstick’.

2. Industry and GIA teaching of methods and recommendations for color grading using GIA Diamond Masters, which reduce the subjectivity of color grading.

3. The pros and cons in the use of CZ master stones in diamond color grading.

4. A study of grading light environments using five lighting types that resulted in additional recommendations for color grading using diamond or CZ master stones.

Was the selection of diamonds to be used done at random and why only 25 stones?

For the Medium, Strong and Very Strong Blues, the 25 diamond database was made up of the first five stones of each strength having post-2000 GIA grading reports that I was able to obtain. The faint and none used as a control were likewise randomly obtained, most with GIA grading reports. Antoinette Matlins happened fortuitously to have the VST Blue cushion #5 that turned out to be the true blue-white top color diamond historically called Jager.

Were the specified light sources the ONLY source of light in the room at the time of grading?

Grading was done in each light in an otherwise relatively dark room.

Finally, remember the grading in GIA DiamondDock standard lighting is by GIA GTL, and AGSL as well as me. As Bryan has pointed out, all three agree within tolerance on the grades of the study's 10 non-fluoresent control diamonds. This close correlation in grading supports the grading skill and consistency of all three. It is only as the strength of the diamond's fluorescence goes from medium to strong to very strong blue that differences and inconsistencies arise and worsen.

Michael, thanks for posting this- but haven't we moved past the point in the discussion regarding GIA and systematic overgrading of MB/SB stones?
It's not happening and there's been no credible evidence shown to substantiate the claim.

Let's agree you saw a stone as a J color that GIA saw as a G and AGSL saw as an H.
Maybe it was an anomaly. Maybe the methods you used produced an errant result- but it's important to make sure this part is clear.
It's possible to find errors in GIA grades- but they are quite rare and indicate no systematic problem

Careful, the spirits of Frank Wade and GIA founder Robert Shipley as well as past GIA graduate gemologists are likely to rise out of their graves and haunt you repeating over and over again "Fluorescent diamonds should be graded at their color in artificial light devoid of ultraviolet radiation, rather than at their daylight appearance."

Remember, the overgrading and inconsistency problem that is clearly documented in the 2010 Study remains even after the GIA switched to the DiamondDock, and was reinforced by studies in Israel by Tom Tashey and the World Gemological Institute (WGI), an international diamond grading and research center of the Israel Diamond Institute (IDI).

Using the DiamondDock with and without UV filter, Tashey and the Israeli graders did not find much difference or improvement from the DiamondLite to the DiamondDock. They found less improvement than the 2010 study's finding of reduction in overgrading from four grades of fluorescence enhancement in the DiamondLite to two grades in the DiamondDock in 3 of the 5 VST Blues.

Michael- the study does not clearly document an overgrading problem at GIA.
If Tom Tashey was here we could debate his methodology, and credentials.
As it is, there's simply no corroboration of your claim- either in the trade itself, or according to public and trade knowledge of GIA grading results.
You only need to look at EGL ( where Tom Tashley worked) to see the sensitivity and resultant complaints of the trade and public to obvious and systematic overgrading.

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael, as I read your paper I have a couple more questions for you. I am personally more experienced with reading medical journals (more specifically pharmaceutical research) and am accustomed to finding the "limitations" section at the end. I am curious as to whether you formulated a list of limitations and what that list may look like?

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?
What sort of master set of stones did you use for your grading of these 25 stones?
Was the selection of diamonds to be used done at random and why only 25 stones?
Were the specified light sources the ONLY source of light in the room at the time of grading?

I hope you don't take these questions as an indication of me trying to poke holes in your study. They are very real questions I would like to know in order to evaluate the study. I happen to come into this discussion feeling like a UV filter should be used for diamond grading and don't see why the use of a filter would be detrimental to the consumer. If UV light is causing a chameleon effect on stones that is dependent upon the lighting it should be eliminated as a variable, especially considering that we don't know why certain fluorescing stones behave one way and others seem to behave another way.

This post by pfunk encompasses most all questions asked about my color grading methodology, limitations and skill asked over many pages by everyone including Sharon, Garry, David and Karl. So this response is to and for everyone who asked.

As a reader, the first question I am asking myself is what are your credentials and training as a diamond grader?

Credentials and training in diamond grading are a subset of gemology credentials. In the US there are two main avenues to a credential in gemology. One is the Diploma Course and examination to obtain the designation FGA (Fellow of the Gemmological Association of Great Britain). The other is the more widely held (in the US) Diploma course and examination to obtain the credential GG ( Graduate Gemologist) at GIA. It is generally acknowledged in the appraisal community that the FGA program is more academically rigorous and challenging, but in the field of diamond grading GIA is the acknowledged leader and their diamond course superior.

My gemology diploma is FGA, and I own and have researched all four generations of GIA Graduate Gemologist courses from the 60's to the present. I hold the certification by the Accredited Gemologist Association, Certified Gemological Laboratory(CGL) and am a Senior Member of that Association. Senior Member status with the National Association of Jewelry Appraisers was attained after years of continuing education in the fields of gemology and appraising.

What sort of master set of stones did you use for your grading of these 25 stones?

I employed my 10 stone set of quarter carat to three-eighth carat masters built during the 80's by sending stones to GIA where their top color grader (now retired) Karen Hurwit graded them as Masters. I also had access to and employed what I believe for several reasons to be the best 10 stone master set Karen ever put together. That set of Lazar Kaplin Ideal cut diamond masters was made for diamond dealer and CZ master manufacturer Barry Ellin. Here is a photo of that master stone set of nine, whole-grade master diamonds from E to L and N from my article "A place for CZ masters in diamond colour grading" in the Journal of Gemmology / 2008 / Volume 31 / No. 3/4.


For those interested in greater depth of understanding of color grading this article:
( http://acagemlab.com/temp/CowingCZ.pdf ) goes way beyond a "Consumer's Report" style evaluation of the two major CZ master sets available and widely in use in the US.

Findings are reported of studies in five areas related to diamond color grading:

1. The historical development by the Gemological Institute of America (GIA) of a color grading standard beginning with the GIA color grading ‘yardstick’.

2. Industry and GIA teaching of methods and recommendations for color grading using GIA Diamond Masters, which reduce the subjectivity of color grading.

3. The pros and cons in the use of CZ master stones in diamond color grading.

4. A study of grading light environments using five lighting types that resulted in additional recommendations for color grading using diamond or CZ master stones.

Was the selection of diamonds to be used done at random and why only 25 stones?

For the Medium, Strong and Very Strong Blues, the 25 diamond database was made up of the first five stones of each strength having post-2000 GIA grading reports that I was able to obtain. The faint and none used as a control were likewise randomly obtained, most with GIA grading reports. Antoinette Matlins happened fortuitously to have the VST Blue cushion #5 that turned out to be the true blue-white top color diamond historically called Jager.

Were the specified light sources the ONLY source of light in the room at the time of grading?

Grading was done in each light in an otherwise relatively dark room.

Finally, remember the grading in GIA DiamondDock standard lighting is by GIA GTL, and AGSL as well as me. As Bryan has pointed out, all three agree within tolerance on the grades of the study's 10 non-fluoresent control diamonds. This close correlation in grading supports the grading skill and consistency of all three. It is only as the strength of the diamond's fluorescence goes from medium to strong to very strong blue that differences and inconsistencies arise and worsen.

Michael, thanks for posting this- but haven't we moved past the point in the discussion regarding GIA and systematic overgrading of MB/SB stones?
It's not happening and there's been no credible evidence shown to substantiate the claim.

Let's agree you saw a stone as a J color that GIA saw as a G and AGSL saw as an H.
Maybe it was an anomaly. Maybe the methods you used produced an errant result- but it's important to make sure this part is clear.
It's possible to find errors in GIA grades- but they are quite rare and indicate no systematic problem

Careful, the spirits of Frank Wade and GIA founder Robert Shipley as well as past GIA graduate gemologists are likely to rise out of their graves and haunt you repeating over and over again "Fluorescent diamonds should be graded at their color in artificial light devoid of ultraviolet radiation, rather than at their daylight appearance."

Remember, the overgrading and inconsistency problem that is clearly documented in the 2010 Study remains even after the GIA switched to the DiamondDock, and was reinforced by studies in Israel by Tom Tashey and the World Gemological Institute (WGI), an international diamond grading and research center of the Israel Diamond Institute (IDI).

Using the DiamondDock with and without UV filter, Tashey and the Israeli graders did not find much difference or improvement from the DiamondLite to the DiamondDock. They found less improvement than the 2010 study's finding of reduction in overgrading from four grades of fluorescence enhancement in the DiamondLite to two grades in the DiamondDock in 3 of the 5 VST Blues.

Michael- the study does not clearly document an overgrading problem at GIA.

This unretouched photo from GIA's library is GIA's own inadvertent documentation of the "systematic overgrading" problem stemming from grading at 2-3 inches from Verilux fluorescent lighting. That "systematic overgrading" is clearly documented to be still occurring to some lesser degree now that grading is done at 7 inches.

If Tom Tashey was here we could debate his methodology, and credentials.

You are one of the few with the chutzpah to debate the credentials of someone with the stature in the industry of Tom Tashey.

As it is, there's simply no corroboration of your claim- either in the trade itself, or according to public and trade knowledge of GIA grading results.

In the appraisal community there is plenty corroboration of the overgrading that continues after the switch to DiamondDock in 2000, but you would call that hearsay evidence.

You only need to look at EGL ( where Tom Tashley worked) to see the sensitivity and resultant complaints of the trade and public to obvious and systematic overgrading.

For the record, Tom Tashey owned EGL LA back in the day, and under him EGL standards were as high and respected as any in the industry.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Chutzpah!
I love that word.

IN this case you have brought someone into this discussion in your defense of this study who's not here to corroborate your opinion.
I don't mean to impugn anyone- it's especially unfair of you to bring Tom into this discussion as he can't either back you up, or defend your claim that he's convinced of GIA current practice to be systematic overgrading.


I notice no appraisers getting involved to back you up on this one Michael. We have some of the best in the business here.
Plus the fact is that it's an important rule not to trust an appraiser that claims his grade carries more validity than one issued by GIA- other than in the case of a clear cut GIA error. Which do happen, but very rarely.

The pictures I posted in this thread are far more informative that the particular GIA pic you cropped out and magnified.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Tom Tashey is a serious and responsible gemologist.
But Michael, I would add that he is also a fan of face up color grading (as am I) and of reintroducing Blue White diamonds since your silly FTC 1938 ruling outlawing the term in sales and marketing (baby out with bath water stuff).

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael I had asked you this earlier, but did not get a reply.
You keep posting this image, but it seems that the images have been 'adjusted'.
The very top row and the very bottom row are from GIA's PDF.
I ask you again please to comment on the variations.
It seems to me that some of the stones in the table down row suggests an alternative interpretation?

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

snip.. There are plenty of things I loath and detest about GIA grading and reporting, but face down D-Z color is not one. (face up and big size differences are)

To add more fuel to the fire-
My remarks are made with respect to D- N+- color.
Starting at around O-P, and moving down into FLY, FY , Intense and Vivid, the job of color grading MB/SB stones becomes exponentially more difficult- because they have more room to change color.
Plus grading at the bottom end of the alphabet is a bitch even for inert stones. The grades are much wider, so it's far more difficult to anticipate exactly what GIA will do.
With regards to GIA color grading of fluoros:
GIA is tougher on fluoros as compared to inert yellow diamonds.
When confronted with a tray of goods in U-V W-X and Y-Z stones, the deepest yellow colors face up in room lighting are always the fluoros.
Some will lighten considerably in sunlight, others less so.
Today I saw an S-T ( GIA graded) that looked as dark as an inert Fancy Light Yellow in normal daytime, non sunny room lighting, face up.
Sure enough- the stone was rated strong blue. It's a cloudy day, but the stone didn't even loose color at the window.
The cutter also showed me some incredibly vivid intense yellow stones- each one was MB/SB, facing up darker than an Intense should.
My takeaway from the way yellow grading is done is that GIA is erring on the conservative side with Yellow diamonds in MB/SB.
I would not call it a mistake as much as simply the way they do it.

Another point which backs up our lack of knowledge on GIA specific procedures is U-Z grading.
The published data says D-Z stones are graded from the pavilion, yet they really do seem to show a continuity with FLY and the darker grades when viewed though the table. That leads me to believe GIA uses techniques that allow them the freedom to look at the U-V, W-X and Y-Z stones face up and consider the diamond in that position as well as pavilion view.


Again, with subjective grades, compromises are a necessity.

I concur David.
One of my secret practices when selecting fancy yellows is to move the stone right up to the lamp tube and watch for bleaching - and it does not only occur with diamonds graded blue fluoro by GIA - there is a small subset of stones that have not been graded as such that loose some color. I think the 2013 GIA article makes that point well - there can be multiple atomic defects that not only have their own effects, but they also react with the effects of neighboring defects.

So folks, I think we all agree with David that grade bleaching in fancy colored diamonds is a real issue.
So all you people on the opposite side of the fence:
SHOULD GIA GTL REMOVE THE UV IN THEIR FANCY COLORED GRADING LIGHTING?

Bump, Michael - and Bryan and Sharon eta al - a simple answer - the earlier answer was rather vague?

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Tom Tashey is a serious and responsible gemologist.
But Michael, I would add that he is also a fan of face up color grading (as am I) and of reintroducing Blue White diamonds since your silly FTC 1938 ruling outlawing the term in sales and marketing (baby out with bath water stuff).

I'll take your word on this Garry.
It's very hard to glean a lot from any sort of professional resume posted online. Tom, my apologies if you read this as a knock on your experience.
That still does not address the issue of Michael speaking for Tom in this discussion- that's really the main issue for me.

I will say that if Tom was here, and also claiming GIA is overgrading ( I don't know that he feels that way) I would have the same questions for him.

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael I had asked you this earlier, but did not get a reply.
You keep posting this image, but it seems that the images have been 'adjusted'.
The very top row and the very bottom row are from GIA's PDF.
I ask you again please to comment on the variations.
It seems to me that some of the stones in the table down row suggests an alternative interpretation?

Garry,

This reply to David was for your benefit also:

This unretouched photo from GIA's library is GIA's own inadvertent documentation of the "systematic overgrading" problem stemming from grading at 2-3 inches from Verilux fluorescent lighting. That "systematic overgrading" is clearly documented to still be occurring to some lesser degree now that grading is done at 7 inches.

The two printed photos originated from the same digitized image, a copy of which was sent to me from the GIA library. The photo was taken in incandescent studio lighting by the renowned pioneers of gem photography, Harold and Erica Van Pelt. It takes some basic digital photography knowledge to recognize that the two photos differ in these printings only in exposure and white balance. The image from GIA's pdf is somewhat over exposed relative to the 2010 study image, and the blue tinted white background is evidence that the pdf image's white balance is slightly biased toward the blue.

Reviewing for those who may have tuned in late:

The face-up photographs were taken in incandescent illumination (pers. comm. photographer, Erica Van Pelt), which (by its nature and intensity) was relatively UV-free. Consequently, these photographs present the opportunity to observe the relative colors among the diamonds in each set unimproved by blue fluorescence.



If there were no over grading, diamonds within each set should look the same color. But they do not. Look, for example, at the face up view of the 6 stone I color set in the top row of Figure 6a, and consider that all these stones are graded “I” color. The I color set’s diamonds have fluorescent strength, from left to right, of: 1. Medium, 2. Very Strong, 3. Faint, 4.Strong, 5. None, and 6. Strong. If you study those six stones in the face up photograph, stones 2, 4 and 6 appear to have substantially more color than the other three in spite of having been graded identically as I ‘s.

It is no coincidence that these are the three with the strongest blue fluorescence. Revealed in this relatively UV-free lighting is the darker color unenhanced by blue fluorescence of the strongly fluorescing members of this I color set. The considerable difference in color of these six identically graded I color diamonds is perfectly correlated with their fluorescent strength. The lower true color is revealed, because this photograph was taken in lighting lacking sufficient UV and VV to stimulate blue fluorescence.

Here is photographic documentation that the strong and very strong fluorescing I colors in the GIA study have been over graded in the UV-containing and fluorescence-stimulating illumination of the DiamondLite.

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

snip.. There are plenty of things I loath and detest about GIA grading and reporting, but face down D-Z color is not one. (face up and big size differences are)

To add more fuel to the fire-
My remarks are made with respect to D- N+- color.
Starting at around O-P, and moving down into FLY, FY , Intense and Vivid, the job of color grading MB/SB stones becomes exponentially more difficult- because they have more room to change color.
Plus grading at the bottom end of the alphabet is a bitch even for inert stones. The grades are much wider, so it's far more difficult to anticipate exactly what GIA will do.
With regards to GIA color grading of fluoros:
GIA is tougher on fluoros as compared to inert yellow diamonds.
When confronted with a tray of goods in U-V W-X and Y-Z stones, the deepest yellow colors face up in room lighting are always the fluoros.
Some will lighten considerably in sunlight, others less so.
Today I saw an S-T ( GIA graded) that looked as dark as an inert Fancy Light Yellow in normal daytime, non sunny room lighting, face up.
Sure enough- the stone was rated strong blue. It's a cloudy day, but the stone didn't even loose color at the window.
The cutter also showed me some incredibly vivid intense yellow stones- each one was MB/SB, facing up darker than an Intense should.
My takeaway from the way yellow grading is done is that GIA is erring on the conservative side with Yellow diamonds in MB/SB.
I would not call it a mistake as much as simply the way they do it.

Another point which backs up our lack of knowledge on GIA specific procedures is U-Z grading.
The published data says D-Z stones are graded from the pavilion, yet they really do seem to show a continuity with FLY and the darker grades when viewed though the table. That leads me to believe GIA uses techniques that allow them the freedom to look at the U-V, W-X and Y-Z stones face up and consider the diamond in that position as well as pavilion view.


Again, with subjective grades, compromises are a necessity.

I concur David.
One of my secret practices when selecting fancy yellows is to move the stone right up to the lamp tube and watch for bleaching - and it does not only occur with diamonds graded blue fluoro by GIA - there is a small subset of stones that have not been graded as such that loose some color. I think the 2013 GIA article makes that point well - there can be multiple atomic defects that not only have their own effects, but they also react with the effects of neighboring defects.

So folks, I think we all agree with David that grade bleaching in fancy colored diamonds is a real issue.
So all you people on the opposite side of the fence:
SHOULD GIA GTL REMOVE THE UV IN THEIR FANCY COLORED GRADING LIGHTING?

Bump, Michael - and Bryan and Sharon eta al - a simple answer - the earlier answer was rather vague?

I personally don't have as much experience with fancy color diamonds, so I may not be aware of reasons why it should not be removed. It seems like the opposite problem - color masking reducing the grade of the diamond - but still a problem in terms of accuracy.

So following the same logic with the normal range stones, I don't know why FCD should not be color graded at their true body color as opposed to the temporarily whitened ("bleached") color. If the bleaching is due to fluorescence then it will not be a problem in the most typical consumer environments.

Is the grading distance the same in The Judge II light box as the diamond dock? And are the grading practices different in terms of how close the grader holds the FCD to the bulbs? Is it standard for them to look for "bleaching" and how does that reflect the grade they render?

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

snip.. There are plenty of things I loath and detest about GIA grading and reporting, but face down D-Z color is not one. (face up and big size differences are)

To add more fuel to the fire-
My remarks are made with respect to D- N+- color.
Starting at around O-P, and moving down into FLY, FY , Intense and Vivid, the job of color grading MB/SB stones becomes exponentially more difficult- because they have more room to change color.
Plus grading at the bottom end of the alphabet is a bitch even for inert stones. The grades are much wider, so it's far more difficult to anticipate exactly what GIA will do.
With regards to GIA color grading of fluoros:
GIA is tougher on fluoros as compared to inert yellow diamonds.
When confronted with a tray of goods in U-V W-X and Y-Z stones, the deepest yellow colors face up in room lighting are always the fluoros.
Some will lighten considerably in sunlight, others less so.
Today I saw an S-T ( GIA graded) that looked as dark as an inert Fancy Light Yellow in normal daytime, non sunny room lighting, face up.
Sure enough- the stone was rated strong blue. It's a cloudy day, but the stone didn't even loose color at the window.
The cutter also showed me some incredibly vivid intense yellow stones- each one was MB/SB, facing up darker than an Intense should.
My takeaway from the way yellow grading is done is that GIA is erring on the conservative side with Yellow diamonds in MB/SB.
I would not call it a mistake as much as simply the way they do it.

Another point which backs up our lack of knowledge on GIA specific procedures is U-Z grading.
The published data says D-Z stones are graded from the pavilion, yet they really do seem to show a continuity with FLY and the darker grades when viewed though the table. That leads me to believe GIA uses techniques that allow them the freedom to look at the U-V, W-X and Y-Z stones face up and consider the diamond in that position as well as pavilion view.


Again, with subjective grades, compromises are a necessity.

I concur David.
One of my secret practices when selecting fancy yellows is to move the stone right up to the lamp tube and watch for bleaching - and it does not only occur with diamonds graded blue fluoro by GIA - there is a small subset of stones that have not been graded as such that loose some color. I think the 2013 GIA article makes that point well - there can be multiple atomic defects that not only have their own effects, but they also react with the effects of neighboring defects.

So folks, I think we all agree with David that grade bleaching in fancy colored diamonds is a real issue.
So all you people on the opposite side of the fence:
SHOULD GIA GTL REMOVE THE UV IN THEIR FANCY COLORED GRADING LIGHTING?

Bump, Michael - and Bryan and Sharon eta al - a simple answer - the earlier answer was rather vague?

I personally don't have as much experience with fancy color diamonds, so I may not be aware of reasons why it should not be removed. It seems like the opposite problem - color masking reducing the grade of the diamond - but still a problem in terms of accuracy.

So following the same logic with the normal range stones, I don't know why FCD should not be color graded at their true body color as opposed to the temporarily whitened ("bleached") color. If the bleaching is due to fluorescence then it will not be a problem in the most typical consumer environments.

Is the grading distance the same in The Judge II light box as the diamond dock? And are the grading practices different in terms of how close the grader holds the FCD to the bulbs? Is it standard for them to look for "bleaching" and how does that reflect the grade they render?

As I understand Bryan the diamonds are further away and graded near the base of the light box - the light in the Judge box is that used by many industries for color matching and considered balanced.
But what David is saying is GIA are stricter on the color of blue fluorescent fancy yellow diamonds. I witnessed this at the HK show 2 months ago when I bought a dozen 1-3ct yellows. I selected the stones that seemed best within their grade from the booth windows (LED illumination) and found most to be fluoro. This supports David's comment that GIA is conservative.
I believe that GIA is now also conservative with the colors from D-H (I do not stock below H) and that many if not all stones appear whiter than their non fluoro equivalents in any light that is good enough to make grade distinctions.
So I guess I am coming to the end of this thread too.
Simply put, the 2010 paper is wrong in real life. If anyone wants to test that, go to any jewelry store and look for your self. Bryan even you could secret shop in Texas.

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

snip.. There are plenty of things I loath and detest about GIA grading and reporting, but face down D-Z color is not one. (face up and big size differences are)

To add more fuel to the fire-
My remarks are made with respect to D- N+- color.
Starting at around O-P, and moving down into FLY, FY , Intense and Vivid, the job of color grading MB/SB stones becomes exponentially more difficult- because they have more room to change color.
Plus grading at the bottom end of the alphabet is a bitch even for inert stones. The grades are much wider, so it's far more difficult to anticipate exactly what GIA will do.
With regards to GIA color grading of fluoros:
GIA is tougher on fluoros as compared to inert yellow diamonds.
When confronted with a tray of goods in U-V W-X and Y-Z stones, the deepest yellow colors face up in room lighting are always the fluoros.
Some will lighten considerably in sunlight, others less so.
Today I saw an S-T ( GIA graded) that looked as dark as an inert Fancy Light Yellow in normal daytime, non sunny room lighting, face up.
Sure enough- the stone was rated strong blue. It's a cloudy day, but the stone didn't even loose color at the window.
The cutter also showed me some incredibly vivid intense yellow stones- each one was MB/SB, facing up darker than an Intense should.
My takeaway from the way yellow grading is done is that GIA is erring on the conservative side with Yellow diamonds in MB/SB.
I would not call it a mistake as much as simply the way they do it.

Another point which backs up our lack of knowledge on GIA specific procedures is U-Z grading.
The published data says D-Z stones are graded from the pavilion, yet they really do seem to show a continuity with FLY and the darker grades when viewed though the table. That leads me to believe GIA uses techniques that allow them the freedom to look at the U-V, W-X and Y-Z stones face up and consider the diamond in that position as well as pavilion view.


Again, with subjective grades, compromises are a necessity.

I concur David.
One of my secret practices when selecting fancy yellows is to move the stone right up to the lamp tube and watch for bleaching - and it does not only occur with diamonds graded blue fluoro by GIA - there is a small subset of stones that have not been graded as such that loose some color. I think the 2013 GIA article makes that point well - there can be multiple atomic defects that not only have their own effects, but they also react with the effects of neighboring defects.

So folks, I think we all agree with David that grade bleaching in fancy colored diamonds is a real issue.
So all you people on the opposite side of the fence:
SHOULD GIA GTL REMOVE THE UV IN THEIR FANCY COLORED GRADING LIGHTING?

Bump, Michael - and Bryan and Sharon eta al - a simple answer - the earlier answer was rather vague?

I personally don't have as much experience with fancy color diamonds, so I may not be aware of reasons why it should not be removed. It seems like the opposite problem - color masking reducing the grade of the diamond - but still a problem in terms of accuracy.

So following the same logic with the normal range stones, I don't know why FCD should not be color graded at their true body color as opposed to the temporarily whitened ("bleached") color. If the bleaching is due to fluorescence then it will not be a problem in the most typical consumer environments.

Is the grading distance the same in The Judge II light box as the diamond dock? And are the grading practices different in terms of how close the grader holds the FCD to the bulbs? Is it standard for them to look for "bleaching" and how does that reflect the grade they render?

As I understand Bryan the diamonds are further away and graded near the base of the light box - the light in the Judge box is that used by many industries for color matching and considered balanced.
But what David is saying is GIA are stricter on the color of blue fluorescent fancy yellow diamonds. I witnessed this at the HK show 2 months ago when I bought a dozen 1-3ct yellows. I selected the stones that seemed best within their grade from the booth windows (LED illumination) and found most to be fluoro. This supports David's comment that GIA is conservative.
I believe that GIA is now also conservative with the colors from D-H (I do not stock below H) and that many if not all stones appear whiter than their non fluoro equivalents in any light that is good enough to make grade distinctions.
So I guess I am coming to the end of this thread too.
Simply put, the 2010 paper is wrong in real life. If anyone wants to test that, go to any jewelry store and look for your self. Bryan even you could secret shop in Texas.

Simply put, no evidence (opinions are not the same as evidence) has been put forth to refute the findings of the 2010 study, the findings of Tashey, the observations made by Rapaport, or the market itself as reflected in price penalties. Nor has there been evidence to support the theory that whitening is taking place as a result of VV levels in normal room lighting. Important aspects of the GIA study support the position that consumers are not deriving the purported appearance benefits of fluorescence so commonly touted by the trade.

And if I decide to secret shop, I think I know where in Texas you are referring me to

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael it is very clear and apparent that the strongest blue fluorescent diamond in this image is also the one with the least color.
You do not know that the lighting for table down was different to that used face up - GIA continually refer to that lighting as "normal" in the 1997 article.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

snip.. There are plenty of things I loath and detest about GIA grading and reporting, but face down D-Z color is not one. (face up and big size differences are)

To add more fuel to the fire-
My remarks are made with respect to D- N+- color.
Starting at around O-P, and moving down into FLY, FY , Intense and Vivid, the job of color grading MB/SB stones becomes exponentially more difficult- because they have more room to change color.
Plus grading at the bottom end of the alphabet is a bitch even for inert stones. The grades are much wider, so it's far more difficult to anticipate exactly what GIA will do.
With regards to GIA color grading of fluoros:
GIA is tougher on fluoros as compared to inert yellow diamonds.
When confronted with a tray of goods in U-V W-X and Y-Z stones, the deepest yellow colors face up in room lighting are always the fluoros.
Some will lighten considerably in sunlight, others less so.
Today I saw an S-T ( GIA graded) that looked as dark as an inert Fancy Light Yellow in normal daytime, non sunny room lighting, face up.
Sure enough- the stone was rated strong blue. It's a cloudy day, but the stone didn't even loose color at the window.
The cutter also showed me some incredibly vivid intense yellow stones- each one was MB/SB, facing up darker than an Intense should.
My takeaway from the way yellow grading is done is that GIA is erring on the conservative side with Yellow diamonds in MB/SB.
I would not call it a mistake as much as simply the way they do it.

Another point which backs up our lack of knowledge on GIA specific procedures is U-Z grading.
The published data says D-Z stones are graded from the pavilion, yet they really do seem to show a continuity with FLY and the darker grades when viewed though the table. That leads me to believe GIA uses techniques that allow them the freedom to look at the U-V, W-X and Y-Z stones face up and consider the diamond in that position as well as pavilion view.


Again, with subjective grades, compromises are a necessity.

I concur David.
One of my secret practices when selecting fancy yellows is to move the stone right up to the lamp tube and watch for bleaching - and it does not only occur with diamonds graded blue fluoro by GIA - there is a small subset of stones that have not been graded as such that loose some color. I think the 2013 GIA article makes that point well - there can be multiple atomic defects that not only have their own effects, but they also react with the effects of neighboring defects.

So folks, I think we all agree with David that grade bleaching in fancy colored diamonds is a real issue.
So all you people on the opposite side of the fence:
SHOULD GIA GTL REMOVE THE UV IN THEIR FANCY COLORED GRADING LIGHTING?

Bump, Michael - and Bryan and Sharon eta al - a simple answer - the earlier answer was rather vague?

I personally don't have as much experience with fancy color diamonds, so I may not be aware of reasons why it should not be removed. It seems like the opposite problem - color masking reducing the grade of the diamond - but still a problem in terms of accuracy.

So following the same logic with the normal range stones, I don't know why FCD should not be color graded at their true body color as opposed to the temporarily whitened ("bleached") color. If the bleaching is due to fluorescence then it will not be a problem in the most typical consumer environments.

Is the grading distance the same in The Judge II light box as the diamond dock? And are the grading practices different in terms of how close the grader holds the FCD to the bulbs? Is it standard for them to look for "bleaching" and how does that reflect the grade they render?

As I understand Bryan the diamonds are further away and graded near the base of the light box - the light in the Judge box is that used by many industries for color matching and considered balanced.
But what David is saying is GIA are stricter on the color of blue fluorescent fancy yellow diamonds. I witnessed this at the HK show 2 months ago when I bought a dozen 1-3ct yellows. I selected the stones that seemed best within their grade from the booth windows (LED illumination) and found most to be fluoro. This supports David's comment that GIA is conservative.
I believe that GIA is now also conservative with the colors from D-H (I do not stock below H) and that many if not all stones appear whiter than their non fluoro equivalents in any light that is good enough to make grade distinctions.
So I guess I am coming to the end of this thread too.
Simply put, the 2010 paper is wrong in real life. If anyone wants to test that, go to any jewelry store and look for your self. Bryan even you could secret shop in Texas.

Simply put, no evidence (opinions are not the same as evidence) has been put forth to refute the findings of the 2010 study, the findings of Tashey, the observations made by Rapaport, or the market itself as reflected in price penalties. Nor has there been evidence to support the theory that whitening is taking place as a result of VV levels in normal room lighting. Important aspects of the GIA study support the position that consumers are not deriving the purported appearance benefits of fluorescence so commonly touted by the trade.

And if I decide to secret shop, I think I know where in Texas you are referring me to

You're correct Bryan, Opinions are not facts. Also correct that it is disingenuous to try to imply that they are. – but the opinion that we are talking about is Michael's. That is the unsubstantiated opinion which is being presented as a fact . Calling his opinion a "study" doesn't make it a fact either. There is no evidence whatsoever that GIA is not doing the job correctly. It is a fact I GIA does not publish their specific grading procedures – and it is a fact that they have not been specifically described here by Michael or anyone else. It is a fact that Garry, I, and many others, are very interested in holding laboratories to high standards. You only need to look at the outrage over EGL grading

About whitening: it is a fact that I have a stone that shows this clearly – in fact many stones. It is a fact I offered to send it to you. It is a fact that you did not accept.

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

snip.. There are plenty of things I loath and detest about GIA grading and reporting, but face down D-Z color is not one. (face up and big size differences are)

To add more fuel to the fire-
My remarks are made with respect to D- N+- color.
Starting at around O-P, and moving down into FLY, FY , Intense and Vivid, the job of color grading MB/SB stones becomes exponentially more difficult- because they have more room to change color.
Plus grading at the bottom end of the alphabet is a bitch even for inert stones. The grades are much wider, so it's far more difficult to anticipate exactly what GIA will do.
With regards to GIA color grading of fluoros:
GIA is tougher on fluoros as compared to inert yellow diamonds.
When confronted with a tray of goods in U-V W-X and Y-Z stones, the deepest yellow colors face up in room lighting are always the fluoros.
Some will lighten considerably in sunlight, others less so.
Today I saw an S-T ( GIA graded) that looked as dark as an inert Fancy Light Yellow in normal daytime, non sunny room lighting, face up.
Sure enough- the stone was rated strong blue. It's a cloudy day, but the stone didn't even loose color at the window.
The cutter also showed me some incredibly vivid intense yellow stones- each one was MB/SB, facing up darker than an Intense should.
My takeaway from the way yellow grading is done is that GIA is erring on the conservative side with Yellow diamonds in MB/SB.
I would not call it a mistake as much as simply the way they do it.

Another point which backs up our lack of knowledge on GIA specific procedures is U-Z grading.
The published data says D-Z stones are graded from the pavilion, yet they really do seem to show a continuity with FLY and the darker grades when viewed though the table. That leads me to believe GIA uses techniques that allow them the freedom to look at the U-V, W-X and Y-Z stones face up and consider the diamond in that position as well as pavilion view.


Again, with subjective grades, compromises are a necessity.

I concur David.
One of my secret practices when selecting fancy yellows is to move the stone right up to the lamp tube and watch for bleaching - and it does not only occur with diamonds graded blue fluoro by GIA - there is a small subset of stones that have not been graded as such that loose some color. I think the 2013 GIA article makes that point well - there can be multiple atomic defects that not only have their own effects, but they also react with the effects of neighboring defects.

So folks, I think we all agree with David that grade bleaching in fancy colored diamonds is a real issue.
So all you people on the opposite side of the fence:
SHOULD GIA GTL REMOVE THE UV IN THEIR FANCY COLORED GRADING LIGHTING?

Bump, Michael - and Bryan and Sharon eta al - a simple answer - the earlier answer was rather vague?

I personally don't have as much experience with fancy color diamonds, so I may not be aware of reasons why it should not be removed. It seems like the opposite problem - color masking reducing the grade of the diamond - but still a problem in terms of accuracy.

So following the same logic with the normal range stones, I don't know why FCD should not be color graded at their true body color as opposed to the temporarily whitened ("bleached") color. If the bleaching is due to fluorescence then it will not be a problem in the most typical consumer environments.

Is the grading distance the same in The Judge II light box as the diamond dock? And are the grading practices different in terms of how close the grader holds the FCD to the bulbs? Is it standard for them to look for "bleaching" and how does that reflect the grade they render?

As I understand Bryan the diamonds are further away and graded near the base of the light box - the light in the Judge box is that used by many industries for color matching and considered balanced.
But what David is saying is GIA are stricter on the color of blue fluorescent fancy yellow diamonds. I witnessed this at the HK show 2 months ago when I bought a dozen 1-3ct yellows. I selected the stones that seemed best within their grade from the booth windows (LED illumination) and found most to be fluoro. This supports David's comment that GIA is conservative.
I believe that GIA is now also conservative with the colors from D-H (I do not stock below H) and that many if not all stones appear whiter than their non fluoro equivalents in any light that is good enough to make grade distinctions.
So I guess I am coming to the end of this thread too.
Simply put, the 2010 paper is wrong in real life. If anyone wants to test that, go to any jewelry store and look for your self. Bryan even you could secret shop in Texas.

Simply put, no evidence (opinions are not the same as evidence) has been put forth to refute the findings of the 2010 study, the findings of Tashey, the observations made by Rapaport, or the market itself as reflected in price penalties. Nor has there been evidence to support the theory that whitening is taking place as a result of VV levels in normal room lighting. Important aspects of the GIA study support the position that consumers are not deriving the purported appearance benefits of fluorescence so commonly touted by the trade.

And if I decide to secret shop, I think I know where in Texas you are referring me to

You're correct Bryan, Opinions are not facts. Also correct that it is disingenuous to try to imply that they are. – but the opinion that we are talking about is Michael's. That is the unsubstantiated opinion which is being presented as a fact . Calling his opinion a "study" doesn't make it a fact either. There is no evidence whatsoever that GIA is not doing the job correctly. It is a fact I GIA does not publish their specific grading procedures – and it is a fact that they have not been specifically described here by Michael or anyone else. It is a fact that Garry, I, and many others, are very interested in holding laboratories to high standards. You only need to look at the outrage over EGL grading

About whitening: it is a fact that I have a stone that shows this clearly – in fact many stones. It is a fact I offered to send it to you. It is a fact that you did not accept.

I guess we have a different concept of what constitutes a fact. Proclaing that you believe something to be true, no matter how many times you may repeat it, does not make it a fact.

I have told you that I will accept any stone (s) that you or Garry want to send me. I will look at it (them) and give you my observations.

What I said was that such an excersize, regardless of the observations obtained, could in no way be considered to have the validity of the work published by Cowing or GIA. I also requested that you please inform me of the details of any shipments you might be sending so that it can be properly received by our logistics folks.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

No. That is not accurate so far. Spend some time reviewing the article and the conversations here.

Furthermore, you act as though GIA is keeping their grading practices a deep dark secret. Every time you make that assertion I just scratch my head. At any given time, all around the world, GIA are training hundreds of new gemologists in their diamond grading methodologies. Some of those students will go on to be graders in the lab themselves. Do you think GIA could keep the knowledge secret, even if for some reason they wanted to?

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

OK fair point about graders being able to speak about the techniques used. Clearly the information is not classified. But there are no current or former GIA employed graders here discussing it. Getting a GG and being a GIA employed grader are two totally separate things.

GIA graded diamonds were exponentially less popular prior to 2000.
It's rare to find a cert that old on the market today to use for comparison- but it's really not relevant to GIA's current practice.
Again to point out- we don't know exactly how GIA is doing it- but we do know they produce very consistent color grades.
Given that I understand how difficult that is to do, I believe GIA is using procedures which make the whole distance from the bulb discussion irrelevant.

The gemologist-appraiser community is periodically given graduate course updates on GTL grading held at GIA that include observation of grading in the lab. With their 2008 article "Color grading “D-to-Z” diamonds at the GIA Laboratory" and these in house graduate seminars GIA has been transparent on "exactly how GIA is doing it"

There is only one way to "make the whole distance from the bulb discussion irrelevant." That is by grading for the true color in lighting that does not stimulate grade whitening fluorescence. That is accomplished either by grading in diffused LED lighting, or UV filtered and diffused fluorescent lighting.

I'm very honored that you finally responded to something I've written Michael- thank you.
Have you witnessed GIA color grading procedures?
If so, when?
How many graders look at the stone?
Are they given an opportunity to look a the stone under any other lighting than the dock?

Michael, I'm starting to feel just like Garry- you'll take a lot of time responding to one question- but can't take a moment to answer a simple series of questions that are integral to the discussion.
I take it you don't have answers to my questions.

Maybe you can answer the questions I posed: specifically - how many graders look at a given stone, and in how many different lighting environments?
Instead of trying the shrug off the very simple points I raise by telling me to re-read the thread, please quote the answers, or answer them specifically- where have I misstated any fact or opinion in my post quoted below?

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

Additionally, if you have other facts that I've missed and are relevant, please share them.

 

[Karl_K]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

He is not the only one, my opinion is that gia is not infallible and there may be some issues.
I just don't know how much and what and where.
Then again my opinion is that color grading practices for diamonds in general is outdated, inaccurate and deeply flawed.
Even if done by machines that could be more accurate than humans it is still being applied in a flawed system.

I will say the 5 biggest issues affecting a diamonds perceived color are:
human vision( a huge variable in itself, for example my vision will never allow me to grade color accurately)
lighting
lighting
lighting
lighting

That means you can not study diamond color without doing a study of lighting and human vision.

It is pretty common knowledge that there are some weird things some diamonds will do with different lighting.
David remember the alien diamond?
You can take a hundred diamonds and study how they react under any given lighting and the 101st could be totally different and not fit in your data set.
Then you ask the question is #101 more common than the other 100?
Even if you have seen 100000 diamonds you can not say for sure because you have only seen preselected diamonds. If your seeing with say only diamonds cut from Canadian rough that does not give you a deep understanding of diamonds cut from rough from other areas.
There is more variety of rough being cut than ever before some of which would have been used for industrial diamonds 10 years ago.
You sit for a minute........
Then you pull your hair out thinking about it.

Back to being a wall wart for me.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Karl,
Sorry I didn't count you in the tally of tradespeople, because you didn't express a clear cut agreement that GIA is overgrading.
But it does seem you agree with my position.
I'm not saying GIA gets it right every time- that's impossible given the fact that there's definitely alien diamonds roaming the earth.
It's impossible for GIA to be right every time for a myriad of reasons.

We also agree that color grading, as it's currently done, is likely not the very best method that could be devised if we re-wrote the rules today.
Taking all that into account, my experience is that GIA's results are as good as could be expected given the physical limitations of current color grading practice, the large volume they handle- and the inconsistency of flouros which exacerbate all of this.
Basically it's not the best system we could dream of but it's the best we have.
Although errors occur, there's certainly no credible evidence that's been shown to prove there's a systematic problem due to lighting.

What's your opinion of the question I posed to Bryan-

IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion?

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

I have not said all of Michaels conclusions are incorrect.
I do believe he has done what most researchers do - i.e. set out to prove a belief he already has. for that reason he is not objective.
e.g. including GIA's very bad pre 200 grading comparisons = scaremongering.
I have not seen any data back up which is mandatory for peer review - e.g. no grading report data base with dates of the grading reports.
Michael does appear to have missed that one exceptional fluoro diamond in the GIA 1997 photo, and his photos does not equal the ones provided in the gIA article for which they were taken.
Just yesterday for example I noted in Rapaport mag April page 51 issue that GIA's new Synthetic diamond sorter also color and size grades small diamonds AND "unlike other machines which require diamonds to be near-colorless or have little to no fluorescence".
So really, the dates of the grading reports is pretty important!
Technology marches on. Old science looking at grading practices 20 and 15 years ago - can be a waste of time.
David and I see lots of diamonds, I dont see a problem today - Michael?

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

No. That is not accurate so far. Spend some time reviewing the article and the conversations here.

Furthermore, you act as though GIA is keeping their grading practices a deep dark secret. Every time you make that assertion I just scratch my head. At any given time, all around the world, GIA are training hundreds of new gemologists in their diamond grading methodologies. Some of those students will go on to be graders in the lab themselves. Do you think GIA could keep the knowledge secret, even if for some reason they wanted to?

Bryan I know for a fact that GIA GTL and GIA education are totally different grading processes. Ask me off line for examples

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

He is not the only one, my opinion is that gia is not infallible and there may be some issues.
I just don't know how much and what and where.
Then again my opinion is that color grading practices for diamonds in general is outdated, inaccurate and deeply flawed.
Even if done by machines that could be more accurate than humans it is still being applied in a flawed system.

I will say the 5 biggest issues affecting a diamonds perceived color are:
human vision( a huge variable in itself, for example my vision will never allow me to grade color accurately)
lighting
lighting
lighting
lighting

That means you can not study diamond color without doing a study of lighting and human vision.

It is pretty common knowledge that there are some weird things some diamonds will do with different lighting.
David remember the alien diamond?
You can take a hundred diamonds and study how they react under any given lighting and the 101st could be totally different and not fit in your data set.
Then you ask the question is #101 more common than the other 100?
Even if you have seen 100000 diamonds you can not say for sure because you have only seen preselected diamonds. If your seeing with say only diamonds cut from Canadian rough that does not give you a deep understanding of diamonds cut from rough from other areas.
There is more variety of rough being cut than ever before some of which would have been used for industrial diamonds 10 years ago.
You sit for a minute........
Then you pull your hair out thinking about it.

Back to being a wall wart for me.

The biggest advance would be what Tom Tashey has wanted for decades - face up colr grading.
The choice of lighting will always be controversial - regular diamond graders lamps are and have never been my favorite - dont use them. I use a single warm white tube for color grading, and it has 2 pieces of lexan UV filter mounted at one end. That tube has far less UV and grade whitening than any other type of tube i have used - I have not tested the UV coming from it - but i know it works. Michael has agreed with me on this off-line.
To test for over-blueness and micklyness I use a cooler higher temp tube.

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

I have not said all of Michaels conclusions are incorrect.
I do believe he has done what most researchers do - i.e. set out to prove a belief he already has. for that reason he is not objective.
e.g. including GIA's very bad pre 200 grading comparisons = scaremongering.
I have not seen any data back up which is mandatory for peer review - e.g. no grading report data base with dates of the grading reports.
Michael does appear to have missed that one exceptional fluoro diamond in the GIA 1997 photo, and his photos does not equal the ones provided in the gIA article for which they were taken.
Just yesterday for example I noted in Rapaport mag April page 51 issue that GIA's new Synthetic diamond sorter also color and size grades small diamonds AND "unlike other machines which require diamonds to be near-colorless or have little to no fluorescence".
So really, the dates of the grading reports is pretty important!
Technology marches on. Old science looking at grading practices 20 and 15 years ago - can be a waste of time.
David and I see lots of diamonds, I dont see a problem today - Michael?

That is really interesting Garry (bolded above). It would be great to get some details on the technology. I cannot seem to find the article online. What is the title of the article?

Perhaps the device uses a light source that does not activate color masking fluorescence?

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

I have not said all of Michaels conclusions are incorrect.
I do believe he has done what most researchers do - i.e. set out to prove a belief he already has. for that reason he is not objective.
e.g. including GIA's very bad pre 200 grading comparisons = scaremongering.
I have not seen any data back up which is mandatory for peer review - e.g. no grading report data base with dates of the grading reports.
Michael does appear to have missed that one exceptional fluoro diamond in the GIA 1997 photo, and his photos does not equal the ones provided in the gIA article for which they were taken.
Just yesterday for example I noted in Rapaport mag April page 51 issue that GIA's new Synthetic diamond sorter also color and size grades small diamonds AND "unlike other machines which require diamonds to be near-colorless or have little to no fluorescence".
So really, the dates of the grading reports is pretty important!
Technology marches on. Old science looking at grading practices 20 and 15 years ago - can be a waste of time.
David and I see lots of diamonds, I dont see a problem today - Michael?

Sorry for the generalization Garry- the specific conclusion I was speaking of is that GIA is systematically overgrading fluoros.
Interesting and important point about the dates of the reports.
Do you agree that having a number of qualified color graders concur with the Michael's grade( or any single grader making such a claim) is also a necessity to back up a claim of overgrading? For me that's a large part of the issue.

 

[Karl_K]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

What's your opinion of the question I posed to Bryan-

IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion?

Just because you are the 800lb gorilla of the industry does not make one the best or always right.
*cough* Microsoft *cough*

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

I have not said all of Michaels conclusions are incorrect.
I do believe he has done what most researchers do - i.e. set out to prove a belief he already has. for that reason he is not objective.
e.g. including GIA's very bad pre 200 grading comparisons = scaremongering.
I have not seen any data back up which is mandatory for peer review - e.g. no grading report data base with dates of the grading reports.
Michael does appear to have missed that one exceptional fluoro diamond in the GIA 1997 photo, and his photos does not equal the ones provided in the gIA article for which they were taken.
Just yesterday for example I noted in Rapaport mag April page 51 issue that GIA's new Synthetic diamond sorter also color and size grades small diamonds AND "unlike other machines which require diamonds to be near-colorless or have little to no fluorescence".
So really, the dates of the grading reports is pretty important!
Technology marches on. Old science looking at grading practices 20 and 15 years ago - can be a waste of time.
David and I see lots of diamonds, I dont see a problem today - Michael?

Sorry for the generalization Garry- the specific conclusion I was speaking of is that GIA is systematically overgrading fluoros.
Interesting and important point about the dates of the reports.
Do you agree that having a number of qualified color graders concur with the Michael's grade( or any single grader making such a claim) is also a necessity to back up a claim of overgrading? For me that's a large part of the issue.

No David - I do not doubt Michaels grading ability. But for his own efficy he should have included others and given he had aces to AGSL lab he could and should have performed testing on their Diamond Dock - and for that matter, given there are questions about the consistency of DD's - then do the same testing on multiple DD's.
However given that GIA have told us they are using machines in the lab, and based on the dates of patents I have seen being lodged, I expect Michael's work is redundant anyway.
(GIA are grading millions of diamonds a year now in their Mumbai lab - why train eyse when you can build a device)

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

I have not said all of Michaels conclusions are incorrect.
I do believe he has done what most researchers do - i.e. set out to prove a belief he already has. for that reason he is not objective.
e.g. including GIA's very bad pre 200 grading comparisons = scaremongering.
I have not seen any data back up which is mandatory for peer review - e.g. no grading report data base with dates of the grading reports.
Michael does appear to have missed that one exceptional fluoro diamond in the GIA 1997 photo, and his photos does not equal the ones provided in the gIA article for which they were taken.
Just yesterday for example I noted in Rapaport mag April page 51 issue that GIA's new Synthetic diamond sorter also color and size grades small diamonds AND "unlike other machines which require diamonds to be near-colorless or have little to no fluorescence".
So really, the dates of the grading reports is pretty important!
Technology marches on. Old science looking at grading practices 20 and 15 years ago - can be a waste of time.
David and I see lots of diamonds, I dont see a problem today - Michael?

That is really interesting Garry (bolded above). It would be great to get some details on the technology. I cannot seem to find the article online. What is the title of the article?

Perhaps the device uses a light source that does not activate color masking fluorescence?

Bryan this is not new news - it was reported (as i wrote) in the current Rapaport magazine. But GIA alluded to digital color grading in one of the GIA G&G papers we have been quoting here. I have mentioned it maybe 20 times.

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan,
I'd wager that we share a concern of how nowadays many people are just stating their opinions, and by doing so loudly and repeatedly, are declaring them "facts"

So let's look at the distinctions here:
Facts:
Michael is claiming GIA is overgrading
This is based on Michael's opinion of a GIA grade ( or grades) on a diamond/diamonds that he examined. We can't factually say that Michael is right, or that GIA is right- because the grades themselves are subjective opinions, as opposed to facts.

Michael has not specified exactly how GIA performs their task of color grading. My opinion is he does not have that information, but the fact is, in this thread he has not clarified exactly how many people look at the diamond, or if it's examined other than in the Dock.

Aside from Michael, we have no one else ( besides you) who is a trade member agreeing with Michael's opinion by posting in this thread.

Opinions:
IN terms of industry, and consumer acceptance, GIA is the leader in Gemological reports at this time. Do you share this opinion Bryan?

Garry and I are of the opinion that Michael's conclusions are incorrect.
You're of the opinion Michael's opinion of GIA grading is correct- is that accurate so far?

I have not said all of Michaels conclusions are incorrect.
I do believe he has done what most researchers do - i.e. set out to prove a belief he already has. for that reason he is not objective.
e.g. including GIA's very bad pre 200 grading comparisons = scaremongering.
I have not seen any data back up which is mandatory for peer review - e.g. no grading report data base with dates of the grading reports.
Michael does appear to have missed that one exceptional fluoro diamond in the GIA 1997 photo, and his photos does not equal the ones provided in the gIA article for which they were taken.
Just yesterday for example I noted in Rapaport mag April page 51 issue that GIA's new Synthetic diamond sorter also color and size grades small diamonds AND "unlike other machines which require diamonds to be near-colorless or have little to no fluorescence".
So really, the dates of the grading reports is pretty important!
Technology marches on. Old science looking at grading practices 20 and 15 years ago - can be a waste of time.
David and I see lots of diamonds, I dont see a problem today - Michael?

That is really interesting Garry (bolded above). It would be great to get some details on the technology. I cannot seem to find the article online. What is the title of the article?

Perhaps the device uses a light source that does not activate color masking fluorescence?

Bryan this is not new news - it was reported (as i wrote) in the current Rapaport magazine. But GIA alluded to digital color grading in one of the GIA G&G papers we have been quoting here. I have mentioned it maybe 20 times.

Automated color grading is not news, nor is the fact that GIA has implemented it as the sole assessment of color on a subset of dossiers. Dan Guillen (30yearsofdiamonds) alluded to it in a pricecscope thread almost two years ago and I confirmed it with GIA. What seems to be news is the part you put in quotes, which indicates that the technology can now accurately grade fluorescent stones.

Understanding more about it, in particular the light source used, would be highly germane to the present discussion.

Post by Texas Leaguer » 18 Jun 2014 17:01
Written by 30yearsofdiamonds » 09 Jun 2014 11:48:
Info that came my way is that on diamond dossier stones, two color grading machines are used to find an agreement on color and if there is a split then human eyes will decide with an opinion. But, maybe someone has heard differently?

Dan, I have confirmed on good authority that you are absolutely correct. Here's a little more detail:

Very few diamonds are actually color graded entirely by machine, and as your post suggested it is confined to diamonds under 1 carat.
The color grading devices that GIA uses are proprietary, developed in-house, and employ spectroscopic analysis. They output more than just a grade on the scale. They will indicate when certain "modifiers" are present such as hues other than yellow and fluorescence. Those stones are referred for human grading. So only the subset of small stones with no modifiers can be color graded entirely by machine.

It was the opinion of the person I talked to that color grading will go more in the direction of device-only grading as the machines continue to get better at taking all the subtle variables into account..