Article Over Grading of Blue Fluorescent Diamonds Revisited

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

As I've mentioned, in looking at a lot of goods I don't find a lot of obvious mistakes in GIA color grading. One shade disputes are relatively common. Two shade disputes between trained graders are very rare.
Certainly never a stone that looked like an F under grading lights and J in any other lighting which was bright enough to differentiate diamond color grades.

Is it possible we can get more details on how the stones in this part of the study were viewed? Specifically can you describe the lighting outside the Diamondlite?

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Hi Michael- thank you for responding.
You're calling a stone which someone claimed "dropped an "F in Diamondlite to a J" as a "textbook example"
Have you seen this particular diamond Michael?
We all ( most) agree there's a whitening effect - however we are taking about a shade or two. I've never seen a stone that shows such a wide disparity. In over 40 years grading.
So there's no way that's any kind of "Textbook example"
If it even exists at all.

Over discounting is not a consumer problem. It is an opportunity.

"Stone 4, (which drops from an F in Diamondlite to a J) is a textbook example of a ‘false colour’ diamond warned about by Wade in 1916."

Stone 4 is a textbook example because, like four out of the five very strong blue data-base diamonds, it is the common type 1A fluorescent diamond that Wade called a ‘false color’. It drops three or four grades down from the grade obtained in the GIA DiamondLite. (Remember that after 2000 GIA switched to grading at 7 inches in the DiamondDock where the VST Blue over grading is reduced from 4 to around 2 grades provided that the diamond is kept 7 inches away from the tubes.)

Thanks to Frank Wade here is a short history of the diamond trade's knowledge and understanding of fluorescent diamonds. It goes way back before GIA's founding:

True Color Versus Fluorescence-Improved Color

A study of the diamond literature of the early 20th century makes it clear the trade was aware of the fluorescence issue. How do we know? Let’s start with the fact that “blue-white” (also called Jager) was the highest established diamond color category at the time. Next, the trade knew that many, if not most, of these stones did not keep their blue-white or snowy white appearance when examined under lighting that stimulated too little fluorescence to improve a stone’s appearance. Dealers were aware that many stones showed a yellow tint when blue-fluorescence wasn’t present to cancel it.

But they were also aware that some rare non-fluorescent blue-white stones and some blue-fluorescent stones called Jager held their pure-white (D-E) color in UV-deficient artificial lighting. It was important in the trade to distinguish between the pretenders and the much rarer and more valuable true blue-white diamonds that held their white color absent fluorescence.

Evidence of these distinctions is found in Frank Wade's 1916 book, Diamonds, A Study of the Factors That Govern their Value. Wade distinguished between diamonds that exhibited a true blue-white appearance and ones of a much more common nature that revealed their yellowish or brownish color in artificial light that did not stimulate blue fluorescence. He correctly attributed the chief cause of the blue-white appearance to fluorescence. He insisted that stones exhibit colorlessness in artificial incandescent light to qualify as true blue-white diamonds.

Wade’s Writing

Through Wade's book and other writings, we are provided with what was insider knowledge of the diamond industry’s grading and valuation practices in the early 20th century.

Quoting from Wade’s book, the top color designation was “River,” closely followed by “Jager.” Wade says: “Probably the finest white diamonds are those classed as Rivers. These stones are either snowy white or bluish white. . . . The finest of the old Indian (Golconda) and Brazilian diamonds, when recut to proper proportions, belong in this classification. . . . A small percentage of African stones belong in this classification.”

“Next after the Rivers, come, perhaps, the so-called “Jagers.” These . . . are bluish white stones. . . .There is really very little difference between some blue-white Rivers and some fine Jagers, and values are closely similar and very high for either class.”

Wade’s writing makes it clear that there were two types of top-color, true blue-white diamonds whose “values are closely similar and very high.” Today we recognize that these two are Type Ia and Type IIa. Characterized by the rarest of the Indian diamonds from the region around the ancient market of Golconda, the non-fluorescent River blue-white is a Type IIa. It is the purest of diamonds having no detectable nitrogen. The Jager blue-white is a Type 1a diamond like some rare stones from the Jagersfontein Mine that contain “aggregated” nitrogen causing their characteristic blue fluorescence.

Wade warned dealers to be “on their guard” against diamonds that “may be very blue when faced up yet brownish or yellowish when seen at some other angle.” He said that few bluish-appearing diamonds are really blue in body color. "Most of them owe their blueness to a bluish fluorescence which becomes more marked the stronger the light. ... Some of these stones are inferior in beauty to pure white stones when viewed under a light which does not cause them to fluoresce."

Of the 5 Type 1A, very strong blue diamonds in the 2010 study only number 5, the 3.02ct D color cushion held its "snowy white" colorlessness absent fluorescence stimulation. It is the one example of a true blue-white diamond historically called Jager.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael I proposed some experiments to detect if VV is making diamonds face up whiter in light good enough to detect slight color differences.
Would you be prepared to participate?

It seems to me this is the crux of the matter. There appears to be agreement that UV in normal indoor lighting is of insufficient intensity to stimulate grade whitening fluorescence. So if there is whitening being observed in normal lighting scenarios, then VV could be a possible cause.

I would think that using the same instruments used in the studies being discussed, you could get readings from a variety of everyday lighting scenarios that would detect the presence and measure the strength of the VV wavelengths (as GIA did in the 2013 study of an assortment of fluoro devices). You could then attempt to stimulate fluoro diamonds with those same wavelengths and strengths and see what is being emitted, if anything.

Brian I mentioned before that the equipment used does not measure VV radiance energy. It cuts off just before the VV.
Both Thomas's multi colored chart and the on from GIA G&G Summer 2013 show that VV plays a role.

It appears to me that Michael Cowing is not interested to participate in any experiment that I have propsed, or to propose one himself?

Garry,
From my reading of both the 2010 Cowing study and the 2013 GIA study (although they were studying different things), the wavelengths capable of stimulating fluorescence in diamonds with N3 centers (the vast majority of all diamonds in the normal range), do not extend beyond 415 nm. In the Thomas Hainswhang tests ( 3D graph in Cowing study) the wavelengths that stimulate fluorescence, including the visible violet, are shown and discussed. It seems relevant to note that the strength of the fluoro stimulated by wavelengths between 400 and 415 as depicted in the graph is much lower than those in the ultraviolet.

Visible light is generally considered to be that with wavelengths greater than 400 nm although there is variability between people in their ability to see light in the range around 400. But there are no wavelengths past 415 that can stimulate fluorescence in N3 centers. Is that your understanding as well?

As you and I agreed earlier, the VV light intensity drops off with distance from the source in the same way the UV drops off. At 3-4 feet from a fluorescent light source the lighting is essentially UV free (less than 1 microwatt). The various gradings of the test stones in the Cowing study show that under 200 foot candles (which is ample to see by) there is no significant whitening taking place, indicating that neither UV nor VV stimulation is happening.

You are welcome to repaet the same statements over and over Bryan.
Meanwhile I will say that I, hundreds of diamond vendors, and many of my clients report a positive whitening experiance in blue fluoro diamonds. Other than Michael Cowing and someone he quotes who died a century ago, I have not heard of users reporting the phenomenon as being negative.
Therefore:
MC has made a case and has not examined outside the invisible range. I remain unconvinced based on the things I see with my own eyes.
Therefore it would be good to conduct a test or experiment with a group of people from both sides to settle the issue.
You can continue to support Micheal, however I have no evidnce of appropriate 'peer review'.
I am a peer. You are a peer, and even David is a peer.

I am not questioning Michaels "repeatability"
I am questioning the basis of the experiment from a face up detectable perspective.

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael I proposed some experiments to detect if VV is making diamonds face up whiter in light good enough to detect slight color differences.
Would you be prepared to participate?

It seems to me this is the crux of the matter. There appears to be agreement that UV in normal indoor lighting is of insufficient intensity to stimulate grade whitening fluorescence. So if there is whitening being observed in normal lighting scenarios, then VV could be a possible cause.

I would think that using the same instruments used in the studies being discussed, you could get readings from a variety of everyday lighting scenarios that would detect the presence and measure the strength of the VV wavelengths (as GIA did in the 2013 study of an assortment of fluoro devices). You could then attempt to stimulate fluoro diamonds with those same wavelengths and strengths and see what is being emitted, if anything.

Brian I mentioned before that the equipment used does not measure VV radiance energy. It cuts off just before the VV.
Both Thomas's multi colored chart and the on from GIA G&G Summer 2013 show that VV plays a role.

It appears to me that Michael Cowing is not interested to participate in any experiment that I have propsed, or to propose one himself?

Garry,
From my reading of both the 2010 Cowing study and the 2013 GIA study (although they were studying different things), the wavelengths capable of stimulating fluorescence in diamonds with N3 centers (the vast majority of all diamonds in the normal range), do not extend beyond 415 nm. In the Thomas Hainswhang tests ( 3D graph in Cowing study) the wavelengths that stimulate fluorescence, including the visible violet, are shown and discussed. It seems relevant to note that the strength of the fluoro stimulated by wavelengths between 400 and 415 as depicted in the graph is much lower than those in the ultraviolet.

Visible light is generally considered to be that with wavelengths greater than 400 nm although there is variability between people in their ability to see light in the range around 400. But there are no wavelengths past 415 that can stimulate fluorescence in N3 centers. Is that your understanding as well?

As you and I agreed earlier, the VV light intensity drops off with distance from the source in the same way the UV drops off. At 3-4 feet from a fluorescent light source the lighting is essentially UV free (less than 1 microwatt). The various gradings of the test stones in the Cowing study show that under 200 foot candles (which is ample to see by) there is no significant whitening taking place, indicating that neither UV nor VV stimulation is happening.

You are welcome to repaet the same statements over and over Bryan.
Meanwhile I will say that I, hundreds of diamond vendors, and many of my clients report a positive whitening experiance in blue fluoro diamonds. Other than Michael Cowing and someone he quotes who died a century ago, I have not heard of users reporting the phenomenon as being negative.
Therefore:
MC has made a case and has not examined outside the invisible range. I remain unconvinced based on the things I see with my own eyes.
Therefore it would be good to conduct a test or experiment with a group of people from both sides to settle the issue.
You can continue to support Micheal, however I have no evidnce of appropriate 'peer review'.
I am a peer. You are a peer, and even David is a peer.

I am not questioning Michaels "repeatability"
I am questioning the basis of the experiment from a face up detectable perspective.

Michael:

We are all in agreement with Garry and his vendors and clients that the whitening effect due to blue fluorescence is a positive experience. Up through the 1970's a premium, not a discount, was paid for these "blue white" diamonds.

Wade's writing, rather than being negative toward blue fluorescing diamonds, said the blue fluorescing stones called “Jagers" had similar very high values as the Rivers (Golconda) diamonds. The top color grades at the time were River and Jager.

So from Wades time through the 70's the trade valued blue fluorescent diamonds as a big positive. The only negative was and still is a blue fluorescing diamond whose color drops from its lab graded color, (as VST Blue #'s 1-4 do) in usual viewing circumstances (indoors out of daylight.)

The consumer and even the grading expert is unlikely to notice this drop from its lab graded color. That determination requires grading expertise and a good set of color comparison masters. Even though he cannot see the difference, does the consumer want to pay for the higher grade that only exists in fluorescence stimulating daylight or in close proximity to the fluorescent light in the labs grading box?

It's like the consumer paying a premium for top clarity grades of Flawless, VVS1 or VVS2. The consumer cannot see the difference, but he or she does not want to pay the higher price if the grade is really VS1.

Even though she cannot see the difference how would the consumer feel that paid E color prices discounted perhaps 10% when she learns that in her home or office lighting the color drops to I worth for example 37% less than E in a one carater VS1? The 2010 study demonstrated this was a common occurrence (four out of five VST blues) with diamonds graded in the GIA DiamondLite from the 60's through the 90's.

By enforcing, since 2000, a grading distance in the DiamondDock of 7 inches, the 2010 study found that the resulting UV reduction takes the typical amount of over grading in Very Strong Blues from as much as four and a half grades down to two grades. With this change in the standard grading light, the potential for over grading was significantly reduced but not eliminated.

Why not just grade the true unenhanced color? Then everyone, especially the consumer, would be happy. As was said: It would remove the distrust and stigma attached to fluorescent diamonds.

The rarer Jager blue-fluorescent diamonds that hold their high-white color in the absence of fluorescence stimulating UV and VV would once more be recognized for their superior beauty and rarity to diamonds that drop in color when not stimulated.

Blue-fluorescent diamonds would then whiten from their graded color, and sometimes appear blue-white in natural daylight.
Promoting this advantage in comparison with non-fluorescent diamonds of similar grade would return the marketing advantage to blue fluorescent diamonds that they once enjoyed.

By grading in lighting that does not stimulate fluorescence, fairness and consistency can be achieved, restoring trust in and rekindling desire for this outstanding gemstone.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael- again, thank you for responding. However you're not answering very simple questions that are at the crux of this issue.
You are claiming 4 grade differences looking first under a fluorescent grading lamp – whatever kind you're talking about is irrelevant to my question.
Specifically, what is the second environment under which you were a viewing this diamond to perceive this 4 shade difference?
What is the lighting like? Remember, for "normal" lighting we would have to take lots of factors into account. Are there windows? What color of the walls? Are there other sources of light?
A four grade shift is unheard of. GIA graders can't see things that are invisible to other experienced graders. Far more likely is that long standing trade members may have a more developed eye than a fair percentage of GIA graders.

In terms of how the trade has reacted: I was trained at a time and place by people that were very familiar with the old color grading system. And I have been in the trade continuously since then – so I have a pretty good idea of how the trade has reacted to florescence over the past 40 years. I agree with Gary what went on 100 years ago doesn't really hold relevance in terms of training today. Even grading prior to 2000 is somewhat distant from the current position GIA holds in the industry.

Unfortunately, most diamond dealers today have no idea of the subtle differences we're talking about in this discussion – they are just trading a piece of paper.
But a real "diamond man" like I grew up with, has the goods in their blood. Fluorescent diamonds can be very beautiful – that is not the issue.
Today, much of colorless Diamond trading is based on other factors beyond how the stone actually looks. Especially when it comes to florescence. But I have yet to see a case where this is a disadvantage to a consumer in colorless stones. Unless they buy one of the small percentage of "bad" fluorescent diamonds. But that is not what we're talking about here.

If anyone else can discuss their experiences with how many shades they have seen a fluoro diamond whiten under grading lamps that would be informative.

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael- again, thank you for responding. However you're not answering very simple questions that are at the crux of this issue.
You are claiming 4 grade differences looking first under a fluorescent grading lamp – whatever kind you're talking about is irrelevant to my question.

It is irrelevant which fluorescent grading lamp is used, because at close grading distances all fluorescent lighting contains significant grade whitening mercury vapor peaks of energy at wavelengths of 365nm in the Ultra Violet and 405nm in the deep Visible Violet.

Specifically, what is the second environment under which you were a viewing this diamond to perceive this 4 shade difference? What is the lighting like? Remember, for "normal" lighting we would have to take lots of factors into account. Are there windows? What color of the walls? Are there other sources of light? A four grade shift is unheard of. GIA graders can't see things that are invisible to other experienced graders. Far more likely is that long standing trade members may have a more developed eye than a fair percentage of GIA graders.

The three to four and a half grade drop of VST Blue diamonds 1-4 from their grade in the DiamondLite was observed and measured 3 feet from this daylight balanced ceiling mounted fluorescent light with its clear plastic diffusing cover. This lighting has a color temperature of 6500 K, and at a distance of 3 ft, an intensity of 200 fc with less than 1 µW/cm² of UV. Almost any artificial ceiling lighting could have been used, since at normal diamond viewing distances such illumination is essentially UV-free and has a visible light intensity under 400fc, which the study data showed did not stimulate noticeable fluorescence. The 3-4.5 grades lower true color was obtained comparing the 25 diamonds to the masters under this lighting.

The other method of seeing and measuring the drop in color absent fluorescence excitation was accomplished in the 2010 Study with the use of a polycarbonate UV filter in front of fluorescent lighting. This method obtains the unenhanced "true color" by filtering the UV in daylight balanced fluorescent lighting down to under 1 µW/cm² and the visible light to under 400 foot candles to avoid stimulation from visible violet.

If anyone else can discuss their experiences with how many shades they have seen a fluoro diamond whiten under grading lamps that would be informative.

The person many would say has the highest "credentials" in diamond grading, and who has seen the color drop four color grades in the DiamondLite with the simple insertion of a thin sheet of polycarbonate is also the first person to discover this drop and bring it to public attention. That man is Thomas E. Tashey, who has been a supervisor of laboratory grading at GIA, an assistant to the Director of the GIA’s Gem Trade Laboratory, operated and directed the European Gemological Laboratory, Los Angeles, CA, and is current owner and director of Professional Gem Sciences Laboratory in Chicago.

In his 2009 Gems and Gemology letter to the editor, Thomas Tashey recounts: “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”.” Tashey also found that diamonds with “medium” to “strong” blue fluorescence generally shifted one to two grades when the filter was used. (The Professional Gemologist, 2000)

This example in a Very-Strong-Blue fluorescent marquise diamond, of a four and a half grade color improvement to high D in the DiamondLite over its unenhanced color grade of low H, may be met with disbelief by professionals in the trade, most all of whom grade in some form of UV-containing fluorescent illumination, and so have not witnessed this large a shift in color. However, the 25-diamond data base in Cowing, 2010. “The overgrading of blue-fluorescent diamonds” contains a 0.63ct marquise diamond with the same four and a half grade improvement in the DiamondLite over its color unimproved by fluorescence.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Micheal have you ever heard of this word?
dictionary.reference.com/browse/demagogue
Dictionary.com
a person, especially an orator or political leader, who gains power and popularity by arousing the emotions, passions, and prejudices of the people rather than by using rational argument.

There is no doubt that some VST blues can be a problem. There are not many anyway.
I have asked many times to conduct a study using N3 Strong Blues.
You keep refering to your articles - that is very annoying.

David please read it so you don't keep getting the same copy and pastes. It is really annoying.

You have not tested or discussed the observation of the color differences in normal lighting.You acknowledge that there is a Visible Violet excitation, you did not use any devices to detect the amount of it.
Until you do consider all possibilities, it is my view that you are preaching and self promoting, and not at all interested in consumer protection.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The three to four and a half grade drop of VST Blue diamonds 1-4 from their grade in the DiamondLite was observed and measured 3 feet from this daylight balanced ceiling mounted fluorescent light with its clear plastic diffusing cover.

So your guy was standing on a chair below a ceiling light?
Were there any other sources of light in the room?
In your opinion, in a "normal" lighting environment, are there other ambient sources of lighting?
3 feet below a ceiling light does not seem how anyone would look at a diamond.

My skepticism is based on real life experience- I've never seen a stone which shifts 4 color grades- my questions are aimed at discovering how such a shift is possible.
I've also never heard anyone else involved in the trade claim a four grade difference was possible.

I've never heard of or met Thomas E. Tashey.
A quick google search shows he last worked for GIA in 1978. So he's far from GIA at this point.
Then he opened and ran an EGL lab in LA- and we all know the reputation of EGL grading.
But if he were here answering, I'd have the same questions.
Besides the fact I don't see any other trade professionals or even consumers who will agree with this supposed 4 grade shift.
Rather than "textbook", if such a stone did exist it would be very rare.

Besides all the other inconsistencies, you're arguing both sides of this debate Michael.
Bryan has been using this article to base his opinion that color whitening is not possible ( due to lack of UV in lighting)- while you are claiming you can coax a four shade difference from a diamond just by changing the lighting.
If a stone was to shift four grades, there'd have to be incremental differences, as the light changes.

BUT in reality, neither position stands up under scrutiny.
The fact is, a small percentage of stones will show color improvement in "typical" lighting which is bright enough to see color.
Remember, most of us live in a world where rooms have windows.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Micheal have you ever heard of this word?
dictionary.reference.com/browse/demagogue
Dictionary.com
a person, especially an orator or political leader, who gains power and popularity by arousing the emotions, passions, and prejudices of the people rather than by using rational argument.

This is a discussion thread on HIS article not on validating your fumblings in trying to poke holes in it, which neither you nor Rockdiamond have succeeded to do in any coherent or substantive manner.

I applaud Michael's patience and I totally understand why he keeps cutting and pasting paragraphs from the literature where one or both of you haven't seem to have read or properly absorbed.

The cumulative VV and UV whitening in the current GIA Diamond dock from 7 inches away has been proven and should not be in dispute. It can cause overgrading of SB and VSB diamonds which the market with imperfect information discounts.

It really doesn't matter what the faceup subjective effect of whitening under undefined or uncontrolled UV and/or VV containing lighting (like a consumer environment). Price is not set by faceup subjective observations, there is no proper correlation between this and the properly controlled facedown grading in a GIA Diamond Dock which is how the value and price is set for D - Z diamonds.

For the purposes of Grading I wholeheartedly agree with Michael's suggestion of using appropriate filters so that there is no whitening and overgrading.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Besides the fact I don't see any other trade professionals or even consumers who will agree with this supposed 4 grade shift.

Of course not because you fail to read or comprehend. What a silly argument you make.

5 grades of whitening requires that particular 0.63 Marquise Diamond with Very Strong Fluoro viewed comparing it with the old GIA Diamondlite (3 inches away) versus an environment where UV and VV is negligible and the light sources that are 3 feet away(36 inches) away.

 

[Karl_K]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Besides the fact I don't see any other trade professionals or even consumers who will agree with this supposed 4 grade shift.
Rather than "textbook", if such a stone did exist it would be very rare.

I believe it exits.
I know at least one diamond that responds to some uv wavelengths and not others.
It is gia none but is also very strong florescent in sunlight and some uv sources.

Are they rare?
No a study of 25 diamonds is not big enough to say if they are or not.
That is why a huge study is needed because diamonds are such a wide range.
Find the normal and find what are the weird and how to tell them apart.
Then we would be talking about something really useful.
But such a study will never be done because it costs a lot of money and in reality it does not the suit the diamond industry to know.
There is a lot of that's good enough so don't change it in the industry.
A lot of that is fear that changing things will kill the market built on a fantasy that equates diamonds with love.

 

[Garry H (Cut Nut)]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Besides the fact I don't see any other trade professionals or even consumers who will agree with this supposed 4 grade shift.

Of course not because you fail to read or comprehend. What a silly argument you make.

5 grades of whitening requires that particular 0.63 Marquise Diamond with Very Strong Fluoro viewed comparing it with the old GIA Diamondlite (3 inches away) versus an environment where UV and VV is negligible and the light sources that are 3 feet away(36 inches) away.

GIA have not used that lighting for 16 years.
GIA also use instrumental color grading.
This article is out of date fear mongering.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Karl- believing something exists, and acutally having seen it are two totally different things.
Anyone who knows diamonds will agree color shifting of MB/SB stones occurs on certain examples. But not four shades.
I've done my own study ( for over 40 years and literally hundreds of thousands of diamonds

Besides the fact I don't see any other trade professionals or even consumers who will agree with this supposed 4 grade shift.

Of course not because you fail to read or comprehend. What a silly argument you make.

5 grades of whitening requires that particular 0.63 Marquise Diamond with Very Strong Fluoro viewed comparing it with the old GIA Diamondlite (3 inches away) versus an environment where UV and VV is negligible and the light sources that are 3 feet away(36 inches) away.

HI Sharonp-
There's some very simple questions that Michael seems to continually avoid.
Who exactly confirmed this 4 grade shift?
How do we know the stone graded J color? Were comparison stones used?
At the end of the day, all we have is the word of the author- and it does not add up. That's why I'm asking the questions I have.

Crucial to the discussion, and proof that the conclusions are false is this:
IN the graph above, there's no specific info about the lighting other than supposed UV/VV measurements and a brief lighting description ( 4 x 32w Phillips bulbs) at 36 inches.
If that is the only lighting in the room, a person would NOT be able to accurately grade color of a diamond. If you've never color graded a diamond, let me tell you- you need plenty of light. Michael has claimed (today) that the light was ceiling mounted.
You could not accurately grade color under these conditions due to insufficient lighting.
So we have both the accuracy of the assessed grade, as well as testing conditions which are clearly in doubt.
I don't see any sort of "proof" whatsoever- and the conclusions do not jibe with reality.


Garry's considerations may be different then mine, but we both see things that do not coincide with reality.

 

[Texas Leaguer]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The discussion seems to have become livelier, which is good. I'm not sure that is for all the right reasons however. In case anyone should notice my absense from the discussion, I will be off the grid for the next week. I look forward to gaining new insights about the topic upon my return. Please talk amongst yourselves

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Have a great vacay Bryan!

Michael- I just went back to the 2010 study to look at the chart- and the key, Identifying you as the grader.
Did you have any peers review the perceived color grades you're claiming?

 

[Karl_K]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Karl- believing something exists, and acutally having seen it are two totally different things.
Anyone who knows diamonds will agree color shifting of MB/SB stones occurs on certain examples. But not four shades.
I've done my own study ( for over 40 years and literally hundreds of thousands of diamonds

Remember the alien asscher? Would you have believed it existed if you hadn't seen it?
There is a lot we don't know about diamonds and there are some that do unexpected things.
The question is how rare and unexpected is it?

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

At the end of the day, all we have is the word of the author- and it does not add up.

What specifically does not add up? Your bias, and grasping at straws to discredit is apparent, it will be hard for you to regain any credibility as an educator in this thread as you have already announced that consumers should ignore the paper.

Crucial to the discussion, and proof that the conclusions are false is this:
IN the graph above, there's no specific info about the lighting other than supposed UV/VV measurements and a brief lighting description ( 4 x 32w Phillips bulbs) at 36 inches.

If that is the only lighting in the room, a person would NOT be able to accurately grade color of a diamond. If you've never color graded a diamond, let me tell you- you need plenty of light. Michael has claimed (today) that the light was ceiling mounted.
You could not accurately grade color under these conditions due to insufficient lighting.

A question about the grading method and environment (which is ALL you have presented) used to grade the color of the diamonds in Lighting 7 does not in of itself invalidate its conclusions.

If you read page 47 of the paper the section entitled 7. Northern daylight balanced ceiling mounted fluorescent light and viewed and view and looked at Figure 11 you would learn more.

It is counter-intuitive to me that 4X32 Watt bulbs of the type in Figure 11 at a distance of 3 feet overhead is not enough to grade diamonds for color. The author states that the intensity at the diamonds is 200fc. What proof do you have that such light is not enough?

GIA has published that they grade diamonds with subdued or low ambient light. I think you have finally asked a reasonable question about the method in Source 7 and I'd like to get an answer before drawing any conclusions on this point.

So we have both the accuracy of the assessed grade, as well as testing conditions which are clearly in doubt.

How about you dial back the rhetoric a few notches and wait for the author to answer.

I'd like to know what Masters he was using and other details of the grading which hopefully the author will share with those who have an open mind(not you!). The conclusions aren't in doubt simply because you ask a question about information not explicit in the paper.

The author has good agreement with Source 3 (in his lab) and GIA-GTL actual grading so if I had to guess his methods(masters used etc.) are sound and at least accurate enough to demonstrate that significant over-grading occurs for SB and VSB diamonds.

It has been borne out in the empirical data that using GIA's Diamond Dock (its current grading environment) the color shift in the most extreme cases is reduced to 2 - 3 grades, you keep referencing one case using GIA's pre 2000 lighting. The overall conclusion is not dependent on that singular example which is not the normal expected shift for VSB diamonds being graded using today's GIA-GTL diamond dock.

Your argument is weak, it is implied that Source 7 is not Diamond Dock conditions or GIA-GTL conditions, the same conclusions can be drawn whether the shift is 2 grades or 4, the data shows the shift to be outside the standard error on the color grading of +/- 1 grade for many of the 25 samples.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Karl- believing something exists, and acutally having seen it are two totally different things.
Anyone who knows diamonds will agree color shifting of MB/SB stones occurs on certain examples. But not four shades.
I've done my own study ( for over 40 years and literally hundreds of thousands of diamonds

Remember the alien asscher? Would you have believed it existed if you hadn't seen it?
There is a lot we don't know about diamonds and there are some that do unexpected things.
The question is how rare and unexpected is it?

This is a very good point Karl- just because someone has not seen something does not mean it does not exist. If any diamond graders reading this have seen a stone shift four shades while color grading, I'd be very interested to hear about it.
IN fact, Fancy Colored diamonds can shift color many shades based on lighting- especially stones with fluoro.

But colorless diamonds behave differently.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

At the end of the day, all we have is the word of the author- and it does not add up.

What specifically does not add up? Your bias, and grasping at straws to discredit is apparent, it will be hard for you to regain any credibility as an educator in this thread as you have already announced that consumers should ignore the paper.

Crucial to the discussion, and proof that the conclusions are false is this:
IN the graph above, there's no specific info about the lighting other than supposed UV/VV measurements and a brief lighting description ( 4 x 32w Phillips bulbs) at 36 inches.

If that is the only lighting in the room, a person would NOT be able to accurately grade color of a diamond. If you've never color graded a diamond, let me tell you- you need plenty of light. Michael has claimed (today) that the light was ceiling mounted.
You could not accurately grade color under these conditions due to insufficient lighting.

A question about the grading method and environment (which is ALL you have presented) used to grade the color of the diamonds in Lighting 7 does not in of itself invalidate its conclusions.

If you read page 47 of the paper the section entitled 7. Northern daylight balanced ceiling mounted fluorescent light and viewed and view and looked at Figure 11 you would learn more.

It is counter-intuitive to me that 4X32 Watt bulbs of the type in Figure 11 at a distance of 3 feet overhead is not enough to grade diamonds for color. The author states that the intensity at the diamonds is 200fc. What proof do you have that such light is not enough?

GIA has published that they grade diamonds with subdued or low ambient light. I think you have finally asked a reasonable question about the method in Source 7 and I'd like to get an answer before drawing any conclusions on this point.

So we have both the accuracy of the assessed grade, as well as testing conditions which are clearly in doubt.

How about you dial back the rhetoric a few notches and wait for the author to answer.

I'd like to know what Masters he was using and other details of the grading which hopefully the author will share with those who have an open mind(not you!). The conclusions aren't in doubt simply because you ask a question about information not explicit in the paper.

The author has good agreement with Source 3 (in his lab) and GIA-GTL actual grading so if I had to guess his methods(masters used etc.) are sound and at least accurate enough to demonstrate that significant over-grading occurs for SB and VSB diamonds.

It has been borne out in the empirical data that using GIA's Diamond Dock (its current grading environment) the color shift in the most extreme cases is reduced to 2 - 3 grades, you keep referencing one case using GIA's pre 2000 lighting. The overall conclusion is not dependent on that singular example which is not the normal expected shift for VSB diamonds being graded using today's GIA-GTL diamond dock.

Your argument is weak, it is implied that Source 7 is not Diamond Dock conditions or GIA-GTL conditions, the same conclusions can be drawn whether the shift is 2 grades or 4, the data shows the shift to be outside the standard error on the color grading of +/- 1 grade for many of the 25 samples.

Hi Sharonp-
Page 47 section 7 is simply repeating factually incorrect statements.
You can NOT color grade diamonds using only typical overhead fl lighting.
I happen to have that sort of lighting in my office. If there was no windows, or it was nighttime I would need to put the diamonds directly under a grading lamp to color grade them. I am not guessing this- I have the diamonds and the lights here, now.
I did underline and bold a passage from your post.
Have you any experience in color grading diamonds? If not, I can tell you that not everyone can see the subtle differences in shade. And if one can, you will need really good light to see the difference between a D and an E. It would be totally impossible using only overhead lighting as described.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

You can NOT color grade diamonds using only typical overhead fl lighting.

I think careful reading goes a long way, 3 feet above a diamond is not "typical overhead lighting".
It may be hanging suspended lighting but it is certainly not typical ceiling lighting mounted 6 - 12 feet above.

Michael can answer what other ambient light is available in the room and how these lamps are 3 feet above, but it doesn't matter.
Source 7 the light from these bulbs at the diamond is stated as 200fc or about 2150 lux. The ambient light is irrelevant it is very weak as compared to this source.

King, Geurts, Gilbertson, and Shigley, 2008. Color grading “D-to-Z” diamonds at the GIA Laboratory. Gems & Gemology, 44(4), 296–321

From the G&G Winter 2008 article on colour grading at GIA GTL, p305, the basic technical specifications for the lighting used for D-Z color grading are:

Stable, fluorescent lamps 17 in. (43 cm) or longer
An intensity of light in the range of 2000-4500lux at the surface of the grading tray

Michael followed GIA's published specs suggested for its color grading. Not enough for you?, go buy a $20 lux meter and measure how much light you think you need at the tray to grade color.

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Sharonp,
Lux meter ordered!
Thanks for the suggestion.

About the lighting Michael is claiming- here's his words

The three to four and a half grade drop of VST Blue diamonds 1-4 from their grade in the DiamondLite was observed and measured 3 feet from this daylight balanced ceiling mounted fluorescent light with its clear plastic diffusing cover.

How do we get a diamond three feet from a ceiling mounted fl lamp, and have it in a position to grade color?
This aspect is also important to verify the claim of the author. If there's aspects which don't seem to jibe in the methodology, it could indicate other inconsistencies.

IN terms of the question I asked- have you any experience color grading diamonds?
If you had, you'd better understand my skepticism.


If you've watched this forum and seen one trade member continually quoting aspects of this paper which are misleading, you'd understand why the discussion gets a bit heated at times.
Specifically- I ( and other trade members) contend that a select number of fluoro diamonds show color improvement due to their fluoro in any lighting situation which is bright enough to distinguish color.
One trade member continually takes the position that it's not possible-by the sole virtue of the claims of this study.
If the study is flawed, the conclusions are not accurate.

 

[michaelgem]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

At the end of the day, all we have is the word of the author- and it does not add up.

What specifically does not add up? Your bias, and grasping at straws to discredit is apparent, it will be hard for you to regain any credibility as an educator in this thread as you have already announced that consumers should ignore the paper.

Crucial to the discussion, and proof that the conclusions are false is this:
IN the graph above, there's no specific info about the lighting other than supposed UV/VV measurements and a brief lighting description ( 4 x 32w Phillips bulbs) at 36 inches.

If that is the only lighting in the room, a person would NOT be able to accurately grade color of a diamond. If you've never color graded a diamond, let me tell you- you need plenty of light. Michael has claimed (today) that the light was ceiling mounted.
You could not accurately grade color under these conditions due to insufficient lighting.

A question about the grading method and environment (which is ALL you have presented) used to grade the color of the diamonds in Lighting 7 does not in of itself invalidate its conclusions.

If you read page 47 of the paper the section entitled 7. Northern daylight balanced ceiling mounted fluorescent light and viewed and view and looked at Figure 11 you would learn more.

It is counter-intuitive to me that 4X32 Watt bulbs of the type in Figure 11 at a distance of 3 feet overhead is not enough to grade diamonds for color. The author states that the intensity at the diamonds is 200fc. What proof do you have that such light is not enough?

GIA has published that they grade diamonds with subdued or low ambient light. I think you have finally asked a reasonable question about the method in Source 7 and I'd like to get an answer before drawing any conclusions on this point.

So we have both the accuracy of the assessed grade, as well as testing conditions which are clearly in doubt.

How about you dial back the rhetoric a few notches and wait for the author to answer.

I'd like to know what Masters he was using and other details of the grading which hopefully the author will share with those who have an open mind(not you!). The conclusions aren't in doubt simply because you ask a question about information not explicit in the paper.

The author has good agreement with Source 3 (in his lab) and GIA-GTL actual grading so if I had to guess his methods(masters used etc.) are sound and at least accurate enough to demonstrate that significant over-grading occurs for SB and VSB diamonds.

It has been borne out in the empirical data that using GIA's Diamond Dock (its current grading environment) the color shift in the most extreme cases is reduced to 2 - 3 grades, you keep referencing one case using GIA's pre 2000 lighting. The overall conclusion is not dependent on that singular example which is not the normal expected shift for VSB diamonds being graded using today's GIA-GTL diamond dock.

Your argument is weak, it is implied that Source 7 is not Diamond Dock conditions or GIA-GTL conditions, the same conclusions can be drawn whether the shift is 2 grades or 4, the data shows the shift to be outside the standard error on the color grading of +/- 1 grade for many of the 25 samples.

Thank you Sharon. Your thorough reading and understanding of the original 2010 Journal of Gemmology article is edifying to me.

Garry and David,

If you ever decide to go professional, you would make a terrific tag team.

Seriously though, You both seem more intent on poking holes in the study and its findings than you are interested in what the study documents and verifies.

You don't accept evidence that Very Strong Blues shift three or four grades from their GIA Lab grade in the DiamondLite to their color unenhanced by fluorescence, even though one of the most respected names in laboratory diamond grading chronicled the fact 16 years ago.

Is there any reason to seriously doubt a man with the credentials of Thom Tashey who reported: “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”.” Tashey also found that diamonds with “medium” to “strong” blue fluorescence generally shifted one to two grades when the filter was used. (The Professional Gemologist, 2000)

Is there any reason to seriously doubt Robert Shipley, the founder of the GIA and the American Gem Society when he addressed this fluorescent diamond grading problem in Gems & Gemology, 1941. There he said: “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).

In that instance the VST Blue, which might have improved four grades from say a J to F in the 600 fc of light intensity and 150 μW/cm2 of UV in the DiamondLite, actually went several more than four grades past D to "distinctly bluish in daylight”. In daylight the UV level can exceed the UV radiometer maximum reading of 2000 μW/cm2 enhancing the color several more than four grades, past D and into the blue.

That's not to say that there aren't a small percentage of white diamonds referred to by Karl that "do unexpected things." However that percentage appears to be less than 1% or 2%. The four of five VST Blue Type 1A's in the study that did shift down in color by three or four grades from their color in the DiamondLite appear to be representative of the majority of VST Blue Type 1A diamonds.

I hasten to remind everyone of the significant change in GIA grading in switching from the DiamondLite to the DiamondDock in 2000. It was likely motivated by the GIA’s 1997 G&G study, “The Effect of Blue Fluorescence on the Appearance of Diamonds” which found a surprising amount of UV in the DiamondLite. (This discovery was especially surprising to gemologists who were taught into the 90’s that the DiamondLite employed “fluorescent lamps designed to produce light fairly close to noon sunlight with insignificant amounts of ultraviolet” in order to grade diamond color unimproved by blue fluorescence.)

The GIA's change at the labs in 2000 from grading in the DiamondLite to requiring grading in the tray of the DiamondDock
resulted in a large reduction in UV and visible light intensity.

That change was from grading at 2 to 3 inches from the DiamondLite tubes to the DiamondDock with its grading tray seven inches from the tubes. The result was a change in the amount of UV excitation from upwards of 150µW/cm2 in the DiamondLite to the vicinity of 30 µW/cm2 at the grading tray in the DiamondDock; a five times reduction. The study found that this amount of UV reduction takes the typical amount of over grading in Very Strong Blues from as much as four and a half grades down to two grades.

With this change in the standard grading light, the potential for over grading was significantly reduced but not eliminated. With lab grading correctly performed at the 7in distance from the tubes to the tray the study results (+2grades in #s 1,2 and 4, +1grade in #3) indicate we should expect a typical two grades of enhancement in VST Blues. That is, except for the rare true blue-whites like diamond #5 that absent fluorescence stimulation still maintain their colorless nature.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Thank you Sharon. Your thorough reading and understanding of the original 2010 Journal of Gemmology article is edifying to me.

You are welcome, could you please provide some details hopefully this will silence some of the critics:

1) The tubes in Source 7 lighting how did you arrange them 3 feet from the diamonds?
2) Were you using GIA master stones and methodologies when you were grading the 25 diamonds in this study in Lighting 7?
3) What did you use to measure the light intensity at the Tray in Lighting 7 and in the other 6 scenarios? How come you don't have a value for the GIA-GTL lightbox?

4) Do you think that the grade whitening for Strong Blue Fluro (not VSB) between GIA-GTL and Source 7 is significant enough for concern?
7 and 8 (2 Grades)
9 (1 Grade)
10 (2 Grades)
15 (0 Grades)
6 (1 Grade) (Assuming your Source 3 is similar enough to GIA-GTL).

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Sharonp,
Lux meter ordered!
Thanks for the suggestion.

Good luck with it, once you have measured Lux from 3 feet from your ceiling lights and also moved the meter close enough to register 2150 lux I think you will be satisfied it is enough light.

Rather than disputing the science what about the market significance of overgrading Fluoro? (Is it really that many diamonds?)
Will you do a rapnet search and pull the answers to these questions:

1) What percentage of all diamonds on offer have VSB?
2) What percentage of all diamonds on offer have SB?
3) What percentage of all diamonds on offer have VSB and are graded with value of DEF?
4) What percentage of all diamonds on offer have SB and are graded DEF?

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Sharonp,
Lux meter ordered!
Thanks for the suggestion.

Good luck with it, once you have measured Lux from 3 feet from your ceiling lights and also moved the meter close enough to register 2150 lux I think you will be satisfied it is enough light.

Rather than disputing the science what about the market significance of overgrading Fluroescence?.
Can you do a rapnet search and pull the answers to these questions:

1) What percentage of all diamonds on offer have VSB?
2) What percentage of all diamonds on offer have SB?
3) What percentage of all diamonds on offer have VSB and are graded with value of DEF?
4) What percentage of all diamonds on offer have SB and are graded DEF?

Still waiting on the answer to my question to you Sharon- do you have experience color grading diamonds?

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Michael, I have only one interest in this thread- educating consumers.
The conclusions reached by the study are incorrect. We can learn why when ( if) you reveal the methodology.
Is there any reason to doubt Garry?- who has put thousands of hours into this forum and scientifically analyzing diamonds.
Is there any reason to doubt me- also having put thousands of hours over many years into sharing inside trade knowledge with the readers?

Shipley's observations do not contradict with what I am saying in any way- are you extrapolating the bold part, or was this actually written by Shipley?

Is there any reason to seriously doubt Robert Shipley, the founder of the GIA and the American Gem Society when he addressed this fluorescent diamond grading problem in Gems & Gemology, 1941. There he said: “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).

In that instance the VST Blue, which might have improved four grades from say a J to F in the 600 fc of light intensity and 150 μW/cm2 of UV in the DiamondLite, actually went several more than four grades past D to "distinctly bluish in daylight”. In daylight the UV level can exceed the UV radiometer maximum reading of 2000 μW/cm2 enhancing the color several more than four grades, past D and into the blue.

The issue boils down to two issues potentially impacting consumers:
1) is there an issue with "overgrading" that should be of concern to consumers?
The answer here is no. I am basing this on 40 years+ of actual color grading experience, as well as about 25 years+ as a diamond buyer.
MB or SB stones in high colors trade at significant discounts. I can say with confidence that the discounts offered on D-E-F MB/SB stones can make them a very attractive bargain for consumers.

2) will certain MB/SB stones exhibit a 1-2 grade improvement when viewed face up under lighting bright enough to see the body color?
My answer here is yes. Historical trade practices back me up on that one

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Still waiting on the answer to my question to you Sharon- do you have experience color grading diamonds?

No, absolutely none, and what relevance does that have to any of this discussion?

Have you ever graded diamonds for GIA-GTL?
Do you think you more capable of 'grading' and assessing what is enough light for 'color grading' than GIA-GTL and its published conditions?

Would you even be able to qualify as a GIA grader today? (Given your age and vision?)
Have you passed any of the tests that GIA staff must pass in order to be eligible as graders?
Have you taken the Dvorine Color Test lately? Matchpoint Metameric Color Rule Test? Farnsworth-Munsell 100 Hue Test?

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

It makes a HUGE difference because you're making assumptions that do not hold true in real life Sharon

I have no interest in working for GIA- but we do submit quite a few stones- and I generally pre-grade before we submit.
My track record on correctly grading color to GIA standards is pretty strong. Like anyone, I will miss by a grade at times- but never more than 2- and 2 is exceptionally rare

In terms of training, I was extremely lucky to have gone to the Harry Winston school of diamond grading. It has held up pretty well

I have been asked to consult for a few of the major gem labs as well.

 

[sharonp]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

It makes a HUGE difference because you're making assumptions that do not hold true in real life Sharon

What assumptions would those be exactly Rockdiamond?

I have no interest in working for GIA- but we do submit quite a few stones- and I generally pre-grade before we submit.

I didn't ask if you wanted to take a job with GIA I asked if you were qualified and had passed there tests please answer my questions one by one as you have brought my credentials into this discussion I want to know if yours hold up and if GIA-GTL would think yours stand up.

My track record on correctly grading color to GIA standards is pretty strong.

Do you own and use a set of master stones Rockdiamond?

In terms of training, I was extremely lucky to have gone to the Harry Winston school of diamond grading. It has held up pretty well

At the Harry Winston School of diamond grading what was the light intensity in lux or fc at the grading tray? How would it compare to today's diamond dock in terms of proximity to the light sources?

 

[Rockdiamond]

Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

It makes a HUGE difference because you're making assumptions that do not hold true in real life Sharon

What assumptions would those be exactly Rockdiamond?
Among others, you're assuming Michael is correct about this four grade color shift. Even if we can find a single stone that would move four colors in a colorless, it would by no means be a "textbook case"- rather if it does exist, it would be an anomaly

I have no interest in working for GIA- but we do submit quite a few stones- and I generally pre-grade before we submit.

I didn't ask if you wanted to take a job with GIA I asked if you were qualified and had passed there tests please answer my questions one by one as you have brought my credentials into this discussion I want to know if yours hold up and if GIA-GTL would think yours stand up.

I have not taken any tests to qualify for GIA- I am certainly qualified to do the job.

My track record on correctly grading color to GIA standards is pretty strong.

Do you own and use a set of master stones Rockdiamond?

Nope- don't need them. I am not an appraiser- but my livelihood depends on me making the correct buying choices. Although I don't use masters, I have plenty of GIA graded stones on hand to use for comparison.
Also, my ability to grade color is quite developed- I have frequently graded the color of stones correctly without a comparison stone.

In terms of training, I was extremely lucky to have gone to the Harry Winston school of diamond grading. It has held up pretty well

At the Harry Winston School of diamond grading what was the light intensity in lux or fc at the grading tray? How would it compare to today's diamond dock in terms of proximity to the light sources?

This was in 1976-1980- no one thought of measuring the light.
The color graders sat by northern facing windows, supplemented by diamond grading lights.
They only worked till about 2pm- and all were female. ( 1970's pc you know

I have read GIA's published literature on methodology-but they never really specify all the procedures.
It is my experience that when grading a person is going to look at the diamond under the light, then outside as well. People grade, and they are not machines.
GIA has shown itself to be very interested in issuing consistent grading, and they've done a pretty good job of it.