Article Over Grading of Blue Fluorescent Diamonds Revisited

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Garry – I will be happy to provide more specifics about the lighting soon.
Let me throw this out there: if we all feel that fluorescent diamonds are being treated unfairly in the market , how does this study help?
Can we all agree that no matter what we discuss here, or no matter how many studies Michael performs, GIA is not going to change its practices because of this.
To me, the solution would be to debunk a study like this, and clarify the issue.
Michael – I deal with consumers every single day. They are very confused about florescence, so they just tend to avoid. This study does nothing to go against the misimpressions about florescence- just the opposite.
Beyond everything else, this is my biggest objection to it.

Here's a great example – the two stones I photographed were obtained for a family friend.
The guy ( who we are not close to) is coming to us to buy a ring for someone who is very close to our family – the recipient.
Between the two stones, the strong blue stone is without a doubt the better purchase in this particular situation. I can say this because I know the recipient and what she wants. And I'm looking at the diamonds.
The guy: "well, I'm concerned that one of her friends might make a bad comment about the florescence."
For this reason our friend will probably end up getting a 2 carat diamond, instead of a 2.60 carat diamond. For no other reason than the fact that florescence is widely misunderstood.
And knowing the recipient, I am quite sure she would prefer a larger diamond.
The point is, for those of us in the trenches – dealing with consumers every day – a study like this is misinformation more than anything else.

 

[Karl_K]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Something that would be interesting is have flats cut to the same thickness, laser a number on each.
Some with v-strong florescence, some med, some with none and different color grades and even different tones if you wanted to. (agree on 3 experts to set the base color grades, ask the labs if they want to play too.)
They could be cut from tops or broken diamonds to keep costs down.
Then do a simple which has less color with different lighting and with different people.
That would help eliminate differences in cut from the equation and would be low value enough to send them around the world to different people.
Could even have consumers get in the game at the PS get together in Vegas.

Interesting Karl - not sure how you grade the color of a flat? Explain more please.

Through the middle of the polished sides would be the most accurate way to get a material grade which is why they need to be the same thickness.
That also syncs the grading position.
This is the way it is done in the material science world all the time, slice and check with the thickness set in the standard.

 

[Karl_K]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

What is frustrating me in this thread and I'm not going to quote anyone because more than one has done so.
For d to z the color grade is supposed to be a material color grade that sets the value.
It is not an appearance grade.
The appearance is greatly affected by lighting, surroundings and cut.
Photos haven even more variables.
Wear a light blue shirt and kick the apparent color of your diamond up for free :}
Should I patent painting a jewelry store blue?

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

What is frustrating me in this thread and I'm not going to quote anyone because more than one has done so.
For d to z the color grade is supposed to be a material color grade that sets the value.
It is not an appearance grade.
The appearance is greatly affected by lighting, surroundings and cut.

Exactly +1, maybe Garry and Rockdiamond would like to create a more general thread where more consumers might participate to discuss appearance and subjective aspects of Fluoro stones because that is not the purpose of this article or thread!

My questions to Michael are not being answered and getting lost in all the tangents.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

No Sharon, its clear that Michael has chosen not answer the considerations raised by pfunk, you , Garry and I.
Sharon- I've also raised questions that you never seem to want to answer...
What exactly is the purpose of this study in your opinion?

BTW- you're certainly welcome to start a different thread.

Karl-GIA purposefully does NOT set values on diamonds. The market does that.
The main utility of a diamond is it's appearance- therefore the appearance will play a major part in the price ( value).
Unless we're selling to blind folks ( no offense intended to any sight impaired people reading this) consumers will look at a diamond to see if they love it- or if they got a good deal.
This is a "safety valve" where the market will punish bad stones regardless of the grade. Eye clean SI2 diamonds bring higher prices than stones where the booger is obvious.
Still an eye clean SI2 costs way less than an ostensibly identical VS1.
Hazy SB stones are near impossible to sell, and not because of what GIA said.
AS it stands today the best MB/SB stones can represent amazing value.


In my opinion consumers are being mislead about fluorescence, and therefore missing good buying opportunities. My opinion is based on many thousands of personal interactions with real life consumers.

PS there's a very famous jewelry outfit that patented a specific blue color

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

A while back I mentioned that knowledge of color grading methodology is an important aspect of this discussion.
FL stones are a bitch to color grade- we all agree on that.
My position- GIA settles upon a fair compromise.
I took these quite informal shots, but maybe they will help.
Both stones graded G by GIA.
One is Strong Blue- the other no fluoro.
Let's start with a shot taken in a light box. I don't have a meter to test for UV, but I have noticed, over photographing literally thousands of diamonds in this box, the lighting is quite bright, yet does not activate fl color change.
To my eye , the SB stone is picking up more color than the non fluoro


Same two stones near a window,indirect sun. Now I can see a bit of that blue, which does make the SB stone look whiter.


Next office light totally shielded from sun- away from a window. In this lighting the inert stone again seems a bit whiter.



These are iphone pics, and sorry for the focus, but I believe they illustrate a bit of color change

Same two stones under the desk with UV penlight


Once we understand color grading- we can see that no matter which light we use, there's going to be other lighting environments where we will get different results. Therefore we have to select a compromise, and use it consistently.
Based on real world diamond results, it is clear that GIA's compromise works very well.

I can not believe no one has been interested in this post David?

It shows what Michael and others are saying - that GIA have overgraded the Fluoro stone, but in a room with daylight lighting the stone has been undergraded.

Is it possible for you to show the position the and distance from the window, rough time of day and direction the sun was coming from, what other lighting was available and if you were blocking that with your body etc. Are the windows double glazed or have any films attached?
If photographs are a security issue then perhaps a simple floor plan sketch?

Your point is not lost on me Garry. It seems everyone is avoiding the main issue- the folks on the other side of this discussion refuse to answer simple, direct questions, and instead keep publishing very cool looking scientific graphs. Or saying that the "study suggests" that you and I ( and gazillions of other consumers and dealers) can't really be seeing what we have been seeing.
My pics DO show something. The indirect sun pic was taken at 5:11 last Thursday.

At that time of the day there is no sun able to hit the floor of my office- as would be the case before about 4pm ( at this time of the year)
We have very large windows and it was still a clear day with strong late afternoon sun, but again, the sun was not shining directly in our office when I took the pic.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

What is frustrating me in this thread and I'm not going to quote anyone because more than one has done so.
For d to z the color grade is supposed to be a material color grade that sets the value.
It is not an appearance grade.
The appearance is greatly affected by lighting, surroundings and cut.

Exactly +1, maybe Garry and Rockdiamond would like to create a more general thread where more consumers might participate to discuss appearance and subjective aspects of Fluoro stones because that is not the purpose of this article or thread!

My questions to Michael are not being answered and getting lost in all the tangents.

Hi Sharon,
Michael put this thread "out there" to some trade organisations as a consumer discussion about fluoro, which sadly it is not.
As the longest person around here, and clearly with a different opinion, and a science education (geologist, which includes mineral science and optics) I can see the dry science - this material is xyz, but this is first and foremost a consumer forum and this thread will be referenced.
Educated consumers like fluoro diamonds. In X or XX years time it is likely that this issue will be resolved and blue fluoro diamonds will be separated from hazy ones (come on GIA!) and this topic will be sorted and lots of PS consumers diamonds will jump up in value.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Hi Sharon,
Michael put this thread "out there" to some trade organisations as a consumer discussion about fluoro, which sadly it is not.
As the longest person around here, and clearly with a different opinion, and a science education (geologist, which includes mineral science and optics)

What does that mean "out there" specifically, and what trade organizations?
I have asked you several times and tried to paraphrase your opinion on this topic on three separate occasions but you don't seem to care.

How do you equate faceup viewing in undefined lighting X environment to color grading facedown in clearly defined Y environment?

Without that linkage you can run all the polls you want or 'experiments' or 'discussions' the results will all be meaningless with respect to color grading.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Same two stones near a window,indirect sun. Now I can see a bit of that blue, which does make the SB stone look whiter.


Next office light totally shielded from sun- away from a window. In this lighting the inert stone again seems a bit whiter.



These are iphone pics, and sorry for the focus, but I believe they illustrate a bit of color change

Same two stones under the desk with UV penlight


Once we understand color grading- we can see that no matter which light we use, there's going to be other lighting environments where we will get different results. Therefore we have to select a compromise, and use it consistently.
Based on real world diamond results, it is clear that GIA's compromise works very well.

My compromise will never include poorly controlled and undefined lighting,poor quality iphone camera pics, bad white balance and any multitude of silly conclusions drawn from these VERY 'unscientific' photographs with a slew of variables you could of controlled but didn't because you are sloppy and NOT a scientist nor do you care one bit about the scientific method.

Are you and Garry going to self appoint yourselves arbiter of what that compromise is? Or let me guess somehow GIA-GTL's grading is the compromise you agree with even though it has no correlation to these sloppy iphone photos or their lighting whatsoever.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Sharon,
I agree, the pics are "raw"
Which to me, adds a certain value.
Most people have iphones and take pics with them- meaning they are familiar with the results.
As opposed to "glamour shots" these are not messed with and I've described how they were taken.
They accurately illustrate what my eyes see looking at the two stones in question.

Are you and Garry going to self appoint yourselves arbiter of what that compromise is? Or let me guess somehow GIA-GTL's grading is the compromise you agree with even though it has no correlation to these sloppy iphone photos or their lighting whatsoever.

We aren't appointing ourselves as anything. We have both observed that GIA is doing a good job grading fl diamonds. I don't need to be a scientist to make that observation.
Garry does have the scientific background, which allows him to deal with the technical issues, but that's not essential to make this observation.
My credentials as a diamond grader more than qualify me to make this observation.
Besides Garry and my observations, there is ZERO evidence that an overgrading problem exists outside this study- and ample opportunity for people to complain right here on PS. Just take a look at discussions regarding EGL grading. If there was a problem, Michael would not be the only voice expressing it.

GIA isn't going to change SQUAT no matter how hard the participants of this discussion try. Nor should they IMO. But again our opinion is not gong to change anything.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Sharon,
I agree, the pics are "raw"
Which to me, adds a certain value.
Most people have iphones and take pics with them- meaning they are familiar with the results.
As opposed to "glamour shots" these are not messed with and I've described how they were taken.
They accurately illustrate what my eyes see looking at the two stones in question.

The fact you took them both table faceup does not make them anywhere close to accurate for grading. I can go on, your lighting is not symmetrical, no enclosed environment, the tables of the two aren't even lined up in your hands, we don't know the intensity of the light, the backgrounds are changing, the background color is not optimal for seeing small nuances in color etc etc.

Are you and Garry going to self appoint yourselves arbiter of what that compromise is? Or let me guess somehow GIA-GTL's grading is the compromise you agree with even though it has no correlation to these sloppy iphone photos or their lighting whatsoever.

We aren't appointing ourselves as anything. We have both observed that GIA is doing a good job grading fl diamonds. I don't need to be a scientist to make that observation.

You just did, You just pronounced judgement on GIA-GTL color accuracy again and once again you based that on what specific data points exactly?

My credentials as a diamond grader more than qualify me to make this observation.

You don't have any credentials as a lab diamond grader, you have already proclaimed too many times you have no idea how GIA-GTL grades diamonds.

Besides Garry and my observations, there is ZERO evidence that an overgrading problem exists outside this study- and ample opportunity for people to complain right here on PS. Just take a look at discussions regarding EGL grading. If there was a problem, Michael would not be the only voice expressing it.

The market knows about this overgrading and has for some time by discounting fluoro stones, its not just a psychological stigma that has led to the discounting, as you said diamonds are bought and sold based on their actual appearance. Even GIA-GTL knows about this overgrading they just have a historical practice to protect. They made a compromise by going halfway in the Diamond Dock which moved the lights from 3 to 7 inches away from the diamonds, Michael would like to see them go even further and has made a compelling argument

Even if you ignore his grading reporting, 30 - 50 uw/cm2 of UV intensity at the diamonds causes whitening.
What next you will tell me he can't even read the light meter in the AGSL/GIA Diamond Dock?

That is not typical intensity UV for indoor viewing full stop. It is also not typical UV intensity for outside viewing either where it could be much more intense. GIA calls this 'equivalent' to "Northern Daylight" but that has more historical or trade significance than it does to consumers viewing environments and they don't claim otherwise. Only you and Garry are making that leap I don't see anyonelse doing so.

So how could GIA-GTL possibly even theoretically be doing a good job their lighting represents no potential consumer lighting?



GIA isn't going to change SQUAT no matter how hard the participants of this discussion try. Nor should they IMO. But again our opinion is not gong to change anything.

That part we agree on, I believe that was posted early on this thread, but it has nothing to do with any argument or criticism of Michael's work.

“Fluorescent stones should be graded at their poorer color [as seen] in artificial light devoid of ultraviolet radiation [i.e., the incandescent bulb of the DiamondLite], rather than at their daylight grade [i.e., the grade they would receive if viewed against a comparison stone in daylight].” (G&G Winter 200

But as we know they didn't measure the UV back then and they are still not doing it this way to this day.

"Realizing that some fluorescent diamonds appeared different when observed under lights with UV content (fluorescent lamps as well as the former Diamolite with its UV source, added in 1947, turned on), GIA made a number of statements related to this with each accompanying modification. In 1955 course material, GIA advised that “This factor should not cause too much difficulty, however, since only a very small percentage of stones fluoresce strongly enough to modify the body color under this light source” (Shipley, 1955, p. 5). (G&G Winter 200

"Regarding the UV component, we have learned that for some fluorescent diamonds the distance between the lamps and the grading tray can influence the final color grade. For consistency, we use a distance of 8–10 in. (20–25 cm) between the lamps and the diamond. Bringing a fluorescent diamond closer to the lamps may result in a stronger fluorescence impact. For instance, a yellow diamond with strong blue fluorescence could appear less yellow (i.e., to have a higher color grade) as it gets closer to the lamps. Moving the same diamond more than 10 in. from the lamps will have the opposite effect; that is, the color will appear more yellow (a lower color grade). " (G&G Winter 200

GIA-GTL does not change anything quickly, abhors changing its historical practices, and this problem only affects a small percentage of diamonds in a significant way according to them so they don't feel the need to change it.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Sharon- the only person who has commented on my pictures on this thread besides you is Garry- who is a trained diamond grader.
While we all agree the pics are very informal, he sees the value and how they illustrate the color change.


I'd also invite Michael or you or anyone else to post photos they think might be illustrative.

I have not said that I don't know how GIA performs color grading specifically- I have said that GIA will not describe specifically the entire procedure of how they color grade diamonds. No one posting in this thread does have the exact procedure currently used.
I have a far more clear idea of what is neccesary than someone not intimately familiar with the task of color grading.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

I'd also invite Michael or you or anyone else to post photos they think might be illustrative.

No and we should all decline because as Karl K has already pointed out they are unsuitable for any precise scientific discussion as they introduce more uncontrolled and undesireable variables.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Sharon, what's your thoughts on using a single grader's opinion and using that for "precise scientific discussion" and "uncontrolled and undesirable variables"

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

What is frustrating me in this thread and I'm not going to quote anyone because more than one has done so.
For d to z the color grade is supposed to be a material color grade that sets the value.
It is not an appearance grade.
The appearance is greatly affected by lighting, surroundings and cut.

Exactly +1, maybe Garry and Rockdiamond would like to create a more general thread where more consumers might participate to discuss appearance and subjective aspects of Fluoro stones because that is not the purpose of this article or thread!

My questions to Michael are not being answered and getting lost in all the tangents.

Sharon,

As time permits, I will answer all your concerns and questions and those of pfunk. Answers have been given to David and Garry, but they are not interested in considering them.

You hit the nail on the head with your statement:

I'd rather GIA-GTL reports its true unenhanced body color and consumers can only 'Win', as certain lighting can only improve it ...(the color would then never be) lower in any lighting than what is printed on the grading report.

The study finding of a three to four grade change from true color to that graded in the DiamondLite continues to be challenged even after hearing of Tom Tashey reporting (Garry, these are exact quotes with reference): “I was shocked when I made the initial discovery, by placing a clear, UV filter, plastic film between the Verilux lamps in the DiamondLite and the diamonds to be graded, that stones with very strong blue fluorescence could change to a lower color by three or four letter grades.” He spoke of a 0.89ct marquise brilliant with Very Strong Blue fluorescence: “In the DiamondLite [Verilux lamps, without UV filter] this stone was graded table down as a high “D”. ... When viewed table down, with the UV filter between the lamps and the diamond, the color grade of the diamond shifted to that of a low “H”.” That is a four and a half grade change.

Even after hearing of GIA's founder Robert Shipley writing: “One of the most important causes of the anomalies that so often trouble a diamond grader is the change of color shown by many fluorescent stones when viewed under different light conditions. Often a fluorescent diamond which appears slightly yellowish under artificial light, appears distinctly bluish in daylight” (Shipley and Liddicoat, 1941). (Old GIA literature calls D-E-F colorless, G-J near colorless and K-M as slightly yellowish).
That "often encountered" change of color was at least 7 grades from its true unenhanced color to D and then to distinctly bluish in natural daylight.

The 2010 study findings would warrant more questions and scrutiny had they not reinforced what is known from Shipley's time and even back to 1915 from Wade's writing.

Why is the following example of data-base diamond #4 glossed over or ignored? It illustrates real, not hypothetical color change along with the amounts of UV and VV that bring about that change.

Take the 1.13ct VST Blue pear brilliant (study diamond #4.) In the DiamondDock lighting GIA-GTL graded it an H, as did I and AGSL .
Absent the blue fluorescence stimulating UV and VV in the DiamondDock lighting the pear's color dropped two grades to a J, its true body color. Though she may not notice this drop of two grades in artificial light, the consumer of this diamond would have paid based upon a color grade that needs the boost of UV and VV to appear an H.

Had the consumer paid based on the unenhanced true color of J she would find her diamond looking as white or whiter than her friend's H color stone when viewed at 7 inches from the jeweler's desk lamp. If the jeweler is Garry, and he takes her near his store windows on a sunny day in Australia she would find that the diamond looks like its F color as graded in the DiamondLite in 150uW of UV and 600fc of illumination. Around noon outside where there is over 1500uW of UV the perceived color would rise past D and into the realm of blue-white. That is over 6 grades of change.

This continuum of color change due to the varying degrees of UV and VV and varying strengths of blue fluorescence is well known and understood. The 2010 study increased this understanding by adding better quantification, (with UV radiometer and light meter measurements), of the impact on grading of diamonds with various strengths of blue fluorescence in the various lighting environments in which they are graded and viewed.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Hi Sharon,
Michael put this thread "out there" to some trade organisations as a consumer discussion about fluoro, which sadly it is not.
As the longest person around here, and clearly with a different opinion, and a science education (geologist, which includes mineral science and optics)

What does that mean "out there" specifically, and what trade organizations?
I have asked you several times and tried to paraphrase your opinion on this topic on three separate occasions but you don't seem to care.

How do you equate faceup viewing in undefined lighting X environment to color grading facedown in clearly defined Y environment?

Without that linkage you can run all the polls you want or 'experiments' or 'discussions' the results will all be meaningless with respect to color grading.

Up to Michael to share who in the trade he invited to read this thread.

Sharon I have written several times in this discussion that in my view when there is enough illumination for consumers to see slight color differences face up that I consider grade whitening is very likely to be occurring hence fluoro is a benefit to consumers (aside from cash savings).

The way we grade diamond color in the industry is fundamentally flawed. Thomas Tashey is the longest most outspoken person on that case.
You can take a rough diamond, cut it in half and cut a round brilliant and a crushed ice cushion from the same rough and get similar table down grades and +2 grades face up lower for the cushion. So 'clearly defined table down' grading is nonsense (not to mention a 1ct G and a 10ct G look totally different in the same cut).

I have not described defined a poll or survey - I have asked participants to suggest something. So far David is the only person who has done anything - he has shown that GIA's grades whithout UV present favour blue fluoro stones but in light with some UV the fluoro stone looks whiter.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

What is frustrating me in this thread and I'm not going to quote anyone because more than one has done so.
For d to z the color grade is supposed to be a material color grade that sets the value.
It is not an appearance grade.
The appearance is greatly affected by lighting, surroundings and cut.

Exactly +1, maybe Garry and Rockdiamond would like to create a more general thread where more consumers might participate to discuss appearance and subjective aspects of Fluoro stones because that is not the purpose of this article or thread!

My questions to Michael are not being answered and getting lost in all the tangents.

Sharon,

As time permits, I will answer all your concerns and questions and those of pfunk. Answers have been given to David and Garry, but they are not interested in considering them.

You hit the nail on the head with your statement:

I'd rather GIA-GTL reports its true unenhanced body color and consumers can only 'Win', as certain lighting can only improve it ...(the color would then never be) lower in any lighting than what is printed on the grading report.

The study finding of a three to four grade change from true color to that graded in the DiamondLite continues to be challenged even after hearing of Tom Tashey reporting (Garry, these are exact quotes with reference): “I was shocked when I made the initial discovery, by placing a clear, UV filter, plastic film between the Verilux lamps in the DiamondLite and the diamonds to be graded, that stones with very strong blue fluorescence could change to a lower color by three or four letter grades.” He spoke of a 0.89ct marquise brilliant with Very Strong Blue fluorescence: “In the DiamondLite [Verilux lamps, without UV filter] this stone was graded table down as a high “D”. ... When viewed table down, with the UV filter between the lamps and the diamond, the color grade of the diamond shifted to that of a low “H”.” That is a four and a half grade change.

Even after hearing of GIA's founder Robert Shipley writing: “One of the most important causes of the anomalies that so often trouble a diamond grader is the change of color shown by many fluorescent stones when viewed under different light conditions. Often a fluorescent diamond which appears slightly yellowish under artificial light, appears distinctly bluish in daylight” (Shipley and Liddicoat, 1941). (Old GIA literature calls D-E-F colorless, G-J near colorless and K-M as slightly yellowish).
That "often encountered" change of color was at least 7 grades from its true unenhanced color to D and then to distinctly bluish in natural daylight.

The 2010 study findings would warrant more questions and scrutiny had they not reinforced what is known from Shipley's time and even back to 1915 from Wade's writing.

Why is the following example of data-base diamond #4 glossed over or ignored? It illustrates real, not hypothetical color change along with the amounts of UV and VV that bring about that change.

Take the 1.13ct VST Blue pear brilliant (study diamond #4.) In the DiamondDock lighting GIA-GTL graded it an H, as did I and AGSL .
Absent the blue fluorescence stimulating UV and VV in the DiamondDock lighting the pear's color dropped two grades to a J, its true body color. Though she may not notice this drop of two grades in artificial light, the consumer of this diamond would have paid based upon a color grade that needs the boost of UV and VV to appear an H.

Had the consumer paid based on the unenhanced true color of J she would find her diamond looking as white or whiter than her friend's H color stone when viewed at 7 inches from the jeweler's desk lamp. If the jeweler is Garry, and he takes her near his store windows on a sunny day in Australia she would find that the diamond looks like its F color as graded in the DiamondLite in 150uW of UV and 600fc of illumination. Around noon outside where there is over 1500uW of UV the perceived color would rise past D and into the realm of blue-white. That is over 6 grades of change.

This continuum of color change due to the varying degrees of UV and VV and varying strengths of blue fluorescence is well known and understood. The 2010 study increased this understanding by adding better quantification, (with UV radiometer and light meter measurements), of the impact on grading of diamonds with various strengths of blue fluorescence in the various lighting environments in which they are graded and viewed.

Michael if you still have access to the J pear shape, would you do a test face up in various consumer type lighting environs - if it is now set - even better.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The study finding of a three to four grade change from true color to that graded in the DiamondLite continues to be challenged even after hearing of Tom Tashey reporting (Garry, these are exact quotes with reference): “I was shocked when I made the initial discovery, by placing a clear, UV filter, plastic film between the Verilux lamps in the DiamondLite and the diamonds to be graded, that stones with very strong blue fluorescence could change to a lower color by three or four letter grades.” He spoke of a 0.89ct marquise brilliant with Very Strong Blue fluorescence: “In the DiamondLite [Verilux lamps, without UV filter] this stone was graded table down as a high “D”. ... When viewed table down, with the UV filter between the lamps and the diamond, the color grade of the diamond shifted to that of a low “H”.” That is a four and a half grade change.
Michael I find it disingenuous to refer ever to Diamondlite and prehistoric history given that consumers who glance here may think this is current reality - which clearly it is not. Tom was also quoted far more consrvatively than the pre DiamondDock grading and post.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Had the consumer paid based on the unenhanced true color of J she would find her diamond looking as white or whiter than her friend's H color stone when viewed at 7 inches from the jeweler's desk lamp. If the jeweler is Garry, and he takes her near his store windows on a sunny day in Australia she would find that the diamond looks like its F color as graded in the DiamondLite in 150uW of UV and 600fc of illumination. Around noon outside where there is over 1500uW of UV the perceived color would rise past D and into the realm of blue-white. That is over 6 grades of change.

For the record, here are 4 photo's taken in my store at 12.30PM on a sunny 15C autumn day. The windows face north east and north - toward the southern hemisphere sun, but the desks where 99% of our diamond viewing is done are 8 to 9 yards from the windows. The lights are mostly LED with 3x 36 watt fluoro tubes. As you can see the ceilings are exceptionally high. I do not have a Lux or UV meter, but I am very sure the numbers you quoted are way too high Michael.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Sharon, what's your thoughts on using a single grader's opinion and using that for "precise scientific discussion" and "uncontrolled and undesirable variables"

Let me see if I can make you understand why Michael Cowing has 1000X more credibility than you do in this thread:

-Head of ACA grading lab
-Dozen or more publications, several on color grading, several on Fluorescence, who published and then had admin post an already peer reviewed article of his.

-The paper contains on Page 46 a table with 25 samples graded in seven different lighting environments or roughly 125 color grades including 42 grades papered by top tier grading laboratories (25 AGSL, 15 GIA-GTL 2 Other) which overlap and corroborate each other.

- Also included in this table and paper almost all variables most importantly the intensity of both UV and VV at the diamonds in all but one of the environments(GIA-GTL) which should be strikingly similar to AGSL.

Then we have your opinion, looks like it took about five minutes to post some attacks to tear down the article, who repeats again and again the same weak argument despite countless hours and days of discussion, your position doesn't appear to have evolved at all in a month. You can't even spend the time to paraphrase or respond to each point being made in this thread let alone the months of work completed by Michael in this paper.

I don't have to believe 4 grades of whitening, don't have to believe even 2 grades of whitening, if its even possibly 0 - 2 grades for all VSB and SB diamonds that would be enough to consider Michael's paper and solution of value.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Up to Michael to share who in the trade he invited to read this thread.

Of course he submitted this article to promote himself and his work on pricescope and to the world, what is your issue with that?

Sharon I have written several times in this discussion that in my view when there is enough illumination for consumers to see slight color differences face up that I consider grade whitening is very likely to be occurring hence fluoro is a benefit to consumers (aside from cash savings).

Then get a lux meter and UV meter and put some numbers and data to that opinion.

The way we grade diamond color in the industry is fundamentally flawed. Thomas Tashey is the longest most outspoken person on that case.
You can take a rough diamond, cut it in half and cut a round brilliant and a crushed ice cushion from the same rough and get similar table down grades and +2 grades face up lower for the cushion. So 'clearly defined table down' grading is nonsense (not to mention a 1ct G and a 10ct G look totally different in the same cut).

I was taught body color is a measure of the rarity of the rough and its value, D color being the most rare and sought after grade in the colorless range. The rough doesn't become more or less rare because of the shape its cut into.

If the rough is cut into a round the light path is short and the body color faceup will be its whitest.
If the rough is cut into a crushed ice radiant the light path is long and the body color as viewed faceup will be significantly more tinted than a round from the same rough.

Why does the current practice have to be changed? If its changed to grading faceup appearance you can forget about all shapes being cut except round in the colorless range. The incentive to the cutters to keep the highest color will trump most other considerations.

I have not described defined a poll or survey - I have asked participants to suggest something. So far David is the only person who has done anything - he has shown that GIA's grades whithout UV present favour blue fluoro stones but in light with some UV the fluoro stone looks whiter.

David hasn't shown or proved anything I can understand. The two of you have bounced around different 'criticisms' of this paper, many of which you have dropped now but still fundamentally you won't separate grading from consumer viewing so I don't see how the direction you are trying to lead discussion is going to be fruitful. Unless you put some numbers on your UV and VV intensity where you see whitening I can't see how it relates to grading environments.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Sharon, what's your thoughts on using a single grader's opinion and using that for "precise scientific discussion" and "uncontrolled and undesirable variables"

Let me see if I can make you understand why Michael Cowing has 1000X more credibility than you do in this thread:

-Head of ACA grading lab
-Dozen or more publications, several on color grading, several on Fluorescence, who published and then had admin post an already peer reviewed article of his.

-The paper contains on Page 46 a table with 25 samples graded in seven different lighting environments or roughly 125 color grades including 42 grades papered by top tier grading laboratories (25 AGSL, 15 GIA-GTL 2 Other) which overlap and corroborate each other.

- Also included in this table and paper almost all variables most importantly the intensity of both UV and VV at the diamonds in all but one of the environments(GIA-GTL) which should be strikingly similar to AGSL.

Then we have your opinion, looks like it took about five minutes to post some attacks to tear down the article, who repeats again and again the same weak argument despite countless hours and days of discussion, your position doesn't appear to have evolved at all in a month. You can't even spend the time to paraphrase or respond to each point being made in this thread let alone the months of work completed by Michael in this paper.

I don't have to believe 4 grades of whitening, don't have to believe even 2 grades of whitening, if its even possibly 0 - 2 grades for all VSB and SB diamonds that would be enough to consider Michael's paper and solution of value.

HI Sharon- if you can take that MASSIVE chip off your shoulder and simply answer the question I posed- I did not even mention Michael.
Given that color grading is a human observation, how can one single grader's opinion- ANY grader- be considered as "precise scientific discussion" and how can it remove "uncontrolled and undesirable variables"
Here's your exact post

I'd also invite Michael or you or anyone else to post photos they think might be illustrative.

No and we should all decline because as Karl K has already pointed out they are unsuitable for any precise scientific discussion as they introduce more uncontrolled and undesireable variables.

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The study finding of a three to four grade change from true color to that graded in the DiamondLite continues to be challenged even after hearing of Tom Tashey reporting (Garry, these are exact quotes with reference): “I was shocked when I made the initial discovery, by placing a clear, UV filter, plastic film between the Verilux lamps in the DiamondLite and the diamonds to be graded, that stones with very strong blue fluorescence could change to a lower color by three or four letter grades.” He spoke of a 0.89ct marquise brilliant with Very Strong Blue fluorescence: “In the DiamondLite [Verilux lamps, without UV filter] this stone was graded table down as a high “D”. ... When viewed table down, with the UV filter between the lamps and the diamond, the color grade of the diamond shifted to that of a low “H”.” That is a four and a half grade change.

Michael I find it disingenuous to refer ever to Diamondlite and prehistoric history given that consumers who glance here may think this is current reality - which clearly it is not. Tom was also quoted far more consrvatively than the pre DiamondDock grading and post.

This continuum of color change due to the varying degrees of UV and VV and varying strengths of blue fluorescence is well known and understood. The 2010 study increased this understanding by adding better quantification, (with UV radiometer and light meter measurements), of the impact on grading of diamonds with various strengths of blue fluorescence in the various lighting environments in which they are graded and viewed.

Garry says: Michael I find it disingenuous to refer ever to Diamondlite and prehistoric history given that consumers who glance here may think this is current reality - which clearly it is not. Tom was also quoted far more conservatively than the pre DiamondDock grading and post.

The references to " prehistoric history" are necessary to document how the trade and GIA handled the grading of blue fluorescent diamonds up through the 90's. The GIA diamond course teaching over the years, quoted at the end of the blue fluorescence revisited article, clearly shows their intent to grade what GIA called the diamond's "true body color" unenhanced by fluorescence:

Gemological Institute of America, 1979. The GIA Diamond Course, Assignment #19, 7-9
"One of the primary requirements for effective diamond color grading is standard lighting. Although daylight, at its best, provides excellent illumination for distinguishing faint nuances of color, it is not a satisfactory standard light source for diamond color grading for reasons (among which) is that the presence of ultraviolet in sunlight will make some stones that exhibit blue fluorescence appear higher in color. Fluorescent diamonds should be graded at their color in artificial light devoid of ultraviolet radiation, rather than at their daylight appearance.

Fluorescent tubes, which produce a balanced light, and are practically devoid of ultraviolet waves, are being manufactured. These tubes are used in the color grading instrument developed by GIA under the trade name DiamondLite.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Sharon, what's your thoughts on using a single grader's opinion and using that for "precise scientific discussion" and "uncontrolled and undesirable variables"

Let me see if I can make you understand why Michael Cowing has 1000X more credibility than you do in this thread:

-Head of ACA grading lab
I am not very familiar with ACA lab- but please explain how being a competitor of GIA lends credibility to Michael's study which is critical of GIA
-Dozen or more publications, several on color grading, several on Fluorescence, who published and then had admin post an already peer reviewed article of his.
Michael has shown us, clearly and with no doubt, that the only "peers" he responds to are those that agree with him. I am not a scientist, but it seems to me that the value of a peer review would be to consider alternative views, or allow others to point out inconsistencies. Kudo to PS mgmt who encouraged a far more thorough review in this thread.

-The paper contains on Page 46 a table with 25 samples graded in seven different lighting environments or roughly 125 color grades including 42 grades papered by top tier grading laboratories (25 AGSL, 15 GIA-GTL 2 Other) which overlap and corroborate each other.

- Also included in this table and paper almost all variables most importantly the intensity of both UV and VV at the diamonds in all but one of the environments(GIA-GTL) which should be strikingly similar to AGSL.
Should being the key word here- we don't know exactly how GIA is doing their grading. Absent that vital piece of data this is not "precise scientific discussion" of GIA color grading

Then we have your opinion, looks like it took about five minutes to post some attacks to tear down the article, who repeats again and again the same weak argument despite countless hours and days of discussion, your position doesn't appear to have evolved at all in a month. You can't even spend the time to paraphrase or respond to each point being made in this thread let alone the months of work completed by Michael in this paper.
I'll admit that in the beginning of the thread I based my objections on the conclusions as opposed to delving deeper into the study. Once I did read more deeply into the study, and learned how the conclusions were reached I became aware of some crucial inconsistencies.
I'll list them again
1) single grader claiming GIA is misgrading, with no independent corroboration
2) using light meter readings to claim whitening is not possible, yet failing to clearly identify the lighting environment these claims are based upon.
One month, and all these posts, and Michael will not answer these simple questions- yet he takes plenty of time to discuss posts agreeing with his conclusions
I don't have to believe 4 grades of whitening, don't have to believe even 2 grades of whitening, if its even possibly 0 - 2 grades for all VSB and SB diamonds that would be enough to consider Michael's paper and solution of value.

We all agree that 2 grades of color change exists based on differences in lighting. That's inherent in color grading of fluorescent diamonds.
Michael's claim that GIA is doing this incorrectly is simply not proved by his study.
Furthermore, by his behavior here in this thread- that being: using non applicable quotes in a misleading manner, and the refusal to respond to the criticisms/ questions that Pfunk, Garry, and I have raised lead me to agree with Garry's point below

The study finding of a three to four grade change from true color to that graded in the DiamondLite continues to be challenged even after hearing of Tom Tashey reporting (Garry, these are exact quotes with reference): “I was shocked when I made the initial discovery, by placing a clear, UV filter, plastic film between the Verilux lamps in the DiamondLite and the diamonds to be graded, that stones with very strong blue fluorescence could change to a lower color by three or four letter grades.” He spoke of a 0.89ct marquise brilliant with Very Strong Blue fluorescence: “In the DiamondLite [Verilux lamps, without UV filter] this stone was graded table down as a high “D”. ... When viewed table down, with the UV filter between the lamps and the diamond, the color grade of the diamond shifted to that of a low “H”.” That is a four and a half grade change.
Michael I find it disingenuous to refer ever to Diamondlite and prehistoric history given that consumers who glance here may think this is current reality - which clearly it is not. Tom was also quoted far more consrvatively than the pre DiamondDock grading and post.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The references to " prehistoric history" are necessary to document how the trade and GIA handled the grading of blue fluorescent diamonds up through the 90's. The GIA diamond course teaching over the years, quoted at the end of the blue fluorescence revisited article, clearly shows their intent to grade what GIA called the diamond's "true body color" unenhanced by fluorescence:

While the historical context and old GIA-GTL practices are interesting I think they do not strengthen your argument for using a filter and diffuser.

We are now in an age of the GIA-GTL DiamondDock and you want GIA-GTL to improve on this, there will likely not be close to 4 grades of whitening expected anymore, you only published one stone out of 5 VST stones that even showed 4 grades of whitening comparing GIA-GTL(or AGSL) to your Source 7, this one stone could have been an anomaly it was only a small 0.63ct Marquise not the best representative example, I'd rather see a 1ct round, your masters weren't Marquise diamonds either.

I think you should concede the overgrading under current GIA-GTL practices may only be in the range of 0 - 2 grades and certainly for the SB diamonds its likely to fall in that range. VSB diamonds are so rare I am not sure they are really are going to drive a change by any laboratory and GIA-GTL has already said as much (see my post above).

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Sharon- if you can take that MASSIVE chip off your shoulder and simply answer the question I posed- I did not even mention Michael.

Stop playing games and wasting everyone's time, or like Bryan I won't respond to you either. You are well aware that you are repeating the same weak argument over and over again. You have posted almost twice as much as anyonelse in this thread, I don't particularly appreciate you drowning out the author's voice on every page.

by Rockdiamond » 09 Mar 2016 12:18
"Was there any independent verification that other graders also perceived this stone as a J?"

Rockdiamond » 14 Mar 2016 18:33
"No matter who is doing the testing, if you're going to try to prove GIA/AGSL are grading incorrectly, you need to have multiple graders corroborate the findings for them to have any sort of weight."

Rockdiamond » 15 Mar 2016 10:29
"Putting all other issues aside, there's no corroboration of Michael's grading. This invalidates any conclusions - other than conclusions drawn by comparing GIA and AGSL grades. Michael could be the best color grader in the world- we'd still need peer review of his grades to take the results seriously."

Rockdiamond » 15 Mar 2016 12:45
"I did notice this from page 307. This backs up what I've been saying about a single color grader."

Rockdiamond » 16 Mar 2016 21:27
"If I was a writer of or a consultant on a paper claiming that GIA or AGSL is misgrading diamonds, I would insist that multiple graders confirm that inaccuracy."

Rockdiamond » 24 Mar 2016 14:48
"Simply put- if we have no independent verification of your grades, how can we trust them? Lest you think I'm singling you our Michael, the same would hold true if any single grader was making these claims."

Rockdiamond » 27 Mar 2016 10:08
"If anyone else published a study claiming GIA is issuing grades that are 4 shades incorrect would you not expect them to prove this by (at the very least) having a second opinion?"

Rockdiamond » 01 Apr 2016 05:54
"Then of course the largest objection – you're claiming a four-grade difference, with no secondary opinion."

Rockdiamond » 05 Apr 2016 09:22
Given that color grading is a human observation, how can one single grader's opinion- ANY grader- be considered as "precise scientific discussion" and how can it remove "uncontrolled and undesirable variables"

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

- Also included in this table and paper almost all variables most importantly the intensity of both UV and VV at the diamonds in all but one of the environments(GIA-GTL) which should be strikingly similar to AGSL.
Should being the key word here- we don't know exactly how GIA is doing their grading. Absent that vital piece of data this is not "precise scientific discussion" of GIA color grading.

The market accepts AGSL and GIA-GTL grading similarly, do you see discounting of AGSL stones compared to GIA-GTL or vice versa? The literature and history of the two organizations also makes it clear that AGSL emulates GIA-GTL in its grading and does a good job of it.

Same dock, same lighting, instead of sticking your head in the sand, why not ask Michael or Jason Quick (Director AGSL) for that matter what the differences(if any) could be in procedures.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Sharon- if you can take that MASSIVE chip off your shoulder and simply answer the question I posed- I did not even mention Michael.

Stop playing games and wasting everyone's time, or like Bryan I won't respond to you either. You are well aware that you are repeating the same weak argument over and over again. You have posted almost twice as much as anyonelse in this thread, I don't particularly appreciate you drowning out the author's voice on every page.

by Rockdiamond » 09 Mar 2016 12:18
"Was there any independent verification that other graders also perceived this stone as a J?"

Rockdiamond » 14 Mar 2016 18:33
"No matter who is doing the testing, if you're going to try to prove GIA/AGSL are grading incorrectly, you need to have multiple graders corroborate the findings for them to have any sort of weight."

Rockdiamond » 15 Mar 2016 10:29
"Putting all other issues aside, there's no corroboration of Michael's grading. This invalidates any conclusions - other than conclusions drawn by comparing GIA and AGSL grades. Michael could be the best color grader in the world- we'd still need peer review of his grades to take the results seriously."

Rockdiamond » 15 Mar 2016 12:45
"I did notice this from page 307. This backs up what I've been saying about a single color grader."

Rockdiamond » 16 Mar 2016 21:27
"If I was a writer of or a consultant on a paper claiming that GIA or AGSL is misgrading diamonds, I would insist that multiple graders confirm that inaccuracy."

Rockdiamond » 24 Mar 2016 14:48
"Simply put- if we have no independent verification of your grades, how can we trust them? Lest you think I'm singling you our Michael, the same would hold true if any single grader was making these claims."

Rockdiamond » 27 Mar 2016 10:08
"If anyone else published a study claiming GIA is issuing grades that are 4 shades incorrect would you not expect them to prove this by (at the very least) having a second opinion?"

Rockdiamond » 01 Apr 2016 05:54
"Then of course the largest objection – you're claiming a four-grade difference, with no secondary opinion."

Rockdiamond » 05 Apr 2016 09:22
Given that color grading is a human observation, how can one single grader's opinion- ANY grader- be considered as "precise scientific discussion" and how can it remove "uncontrolled and undesirable variables"

THANK YOU Sharon for pointing our 9 instances of me asking.
Now please show us where my consideration/question about this glaring inconsistency was responded to by Michael, or Bryan, or you-

Kind of moot- because at this point even you agree there's no evidence whatsoever that GIA is incorrectly grading fl stones. But not moot is how Michael refuses to even discuss my consideration.

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The references to " prehistoric history" are necessary to document how the trade and GIA handled the grading of blue fluorescent diamonds up through the 90's. The GIA diamond course teaching over the years, quoted at the end of the blue fluorescence revisited article, clearly shows their intent to grade what GIA called the diamond's "true body color" unenhanced by fluorescence:

While the historical context and old GIA-GTL practices are interesting I think they do not strengthen your argument for using a filter and diffuser.

We are now in an age of the GIA-GTL DiamondDock and you want GIA-GTL to improve on this, there will likely not be close to 4 grades of whitening expected anymore, you only published one stone out of 5 VST stones that even showed 4 grades of whitening comparing GIA-GTL(or AGSL) to your Source 7, this one stone could have been an anomaly it was only a small 0.63ct Marquise not the best representative example, I'd rather see a 1ct round, your masters weren't Marquise diamonds either.

I think you should concede the overgrading under current GIA-GTL practices may only be in the range of 0 - 2 grades and certainly for the SB diamonds its likely to fall in that range. VSB diamonds are so rare I am not sure they are really are going to drive a change by any laboratory and GIA-GTL has already said as much (see my post above).

Sharon, with regard to the sentence which I bolded above, he does acknowledge that the situation was improved in 2000 with the introduction of the DiamondDock and the lengthened grading distance.

The change in the lighting characteristics from the DL lighting environment containing upwards of 150 µW/cm2
to DD lighting having in the vicinity of 30 µW/cm2 was seen to reduce the typical amount of overgrading in Very
Strong Blues from as much as four grades to two grades. With this change in the standard grading light the potential for
over grading has been reduced but not eliminated.

He is reporting that based upon his study using diamonds with GIA reports dated post 2000, there is still a problem. Though the grading distance was lengthened there is still enough UV and VV to stimulate grade whitening fluorescence and therefore potential color grading inaccuracy.

And I think part of the value of the historical perspective that he provides is to demonstrate the relationship between different devices and practices, and how the extent of problem has changed over time and where it stands today.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The change in the lighting characteristics from the DL lighting environment containing upwards of 150 µW/cm2
to DD lighting having in the vicinity of 30 µW/cm2 was seen to reduce the typical amount of overgrading in Very
Strong Blues from as much as four grades to two grades. With this change in the standard grading light the potential for
over grading has been reduced but not eliminated.

No problem with the paper or the quoted statement, however is up to two grades(and that still has a level of grading reading error) enough to necessitate a change?


I beleive that statement is what is important so talking about Diamondlite or four grades of whitening is the wrong emphasis in this thread in the present post Diamond Dock era.

GIA-GTL only went halfway because they still wanted their grading environment to loosely represent "Northern Daylight" to satisfy consistency with old GIA-GTL and trade practices. They didn't explain their choices though with any data, explain what longwave UV intensity should be included, or explain why the intensity of the visible light should be between 2000 - 4500 lux in the 2008 G&G article.