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Article: Over Grading of Blue Fluorescent Diamonds Revisited

sharonp

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Rockdiamond|1459878760|4015766 said:
THANK YOU Sharon for pointing our 9 instances of me asking.
Now please show us where my consideration/question about this glaringinconsistency was responded to by Michael, or Bryan, or you-
That is not a question, your statement is an annoying restatement over and over again of your negative opinion and questioning of Michael's grading accuracy that doesn't deserve a response.

The fact that Michael is reporting his own findings (not that of three lab graders) isn't in itself a 'glaring inconsistency'(you really should look up what that word means) it just adds potential uncertainty to the grades reported.

Michael has addressed the applicability of his study fairly and he isn't reporting all VSB diamonds will whiten 4 grades +/- 2 he kept it more general as a trend recognizing the inherent reading error. The trend in my mind is enough to want to seek a solution as he has proposed.

If you admit that 2 grades of whitening is very likely than the real question is why should that be the acceptable status quo? Consumers will never know if its 0, 1 or 2 grades of whitening, will you?
 

Texas Leaguer

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

sharonp|1459880253|4015782 said:
Texas Leaguer|1459878804|4015767 said:
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.
It seems to me that any level of inaccuracy that could be controlled for in a practical manner, probably should be. The labs have many rigorous processes, carefully vetted masters, extensive grader training, redundant grading, and other safeguards all aimed at accuracy and consistency.

Nobody here in this overly contentious thread is arguing that activated blue fluorescence cannot cause grade whitening. GIA has a long history of teaching/cautioning about it. So, it seems that from a consumer protection perspective, safeguarding the integrity of the color grade would be a continuing priority.

Why does it make sense for GIA to require color masters to be inert, but color grade blue fluorescent stones against them in light capable of stimulating color masking of the diamond being graded?
 

Rockdiamond

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

sharonp|1459881662|4015793 said:
Rockdiamond|1459878760|4015766 said:
THANK YOU Sharon for pointing our 9 instances of me asking.
Now please show us where my consideration/question about this glaringinconsistency was responded to by Michael, or Bryan, or you-
That is not a question, your statement is an annoying restatement over and over again of your negative opinion and questioning of Michael's grading accuracy that doesn't deserve a response.

The fact that Michael is reporting his own findings (not that of three lab graders) isn't in itself a 'glaring inconsistency'(you really should look up what that word means) it just adds potential uncertainty to the grades reported.

Michael has addressed the applicability of his study fairly and he isn't reporting all VSB diamonds will whiten 4 grades +/- 2 he kept it more general as a trend recognizing the inherent reading error. The trend in my mind is enough to want to seek a solution as he has proposed.

If you admit that 2 grades of whitening is very likely than the real question is why should that be the acceptable status quo? Consumers will never know if its 0, 1 or 2 grades of whitening, will you?
Hi Sharon,
If Michael is sitting around a table claiming a 4 grade difference, hey, let's have another beer.

But calling this a "precise scientific discussion" which is based on an unsupported claim by a single grader is a problem. I used the term inconsistency, but if you have a better one, please.....
That's not a question, it's a statement- but in any case Michael has not addressed it.

It's important for consumers to realize that this study is simply based on Michael's opinion, as opposed to scientific data.

Yes, I know that it's possible for there to be a 2 grade discrepancy on SB stones.
As I've stated- the potential for color change in SB stones is far greater in some stones than others- based on a myriad of factors.
For this reason there's going to be inconsistency in grading even if a machine was doing it.
But it's humans issuing and or checking the grades- so we have that.

You asked earlier about parity between GIA and AGSL.
For the most part, my experience is that it does exist.
BUT- lab shopping is a common technique used by cutters dealers.
We recently needed a "commercial" 4 ct diamond.
When a cutter/friend told me they had an aggressively priced AGSL J/SI2 I was very interested to see it.
I'd bet my bottom dollar that stone had visited GIA and gotten either K color, or I1 clarity or both.
It was a borderline stone on both counts.
This points out the fact that color and clarity grading is NOT a precise science. And it never will be.
 

Rockdiamond

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Texas Leaguer|1459883898|4015810 said:
sharonp|1459880253|4015782 said:
Texas Leaguer|1459878804|4015767 said:
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.
It seems to me that any level of inaccuracy that could be controlled for in a practical manner, probably should be. The labs have many rigorous processes, carefully vetted masters, extensive grader training, redundant grading, and other safeguards all aimed at accuracy and consistency.

Nobody here in this overly contentious thread is arguing that activated blue fluorescence cannot cause grade whitening. GIA has a long history of teaching/cautioning about it. So, it seems that from a consumer protection perspective, safeguarding the integrity of the color grade would be a continuing priority.

Why does it make sense for GIA to require color masters to be inert, but color grade blue fluorescent stones against them in light capable of stimulating color masking of the diamond being graded?
Bryan, I am inviting you ....please- let's bury the hatchet. Part of the conflict between you and I on this study is the aspect of whitening, and can consumers see this whitening. Based on the post of yours I'm quoting, we seem to agree that it's possible for consumers to see a whitening under certain lighting. Can we agree on this point?
 

Texas Leaguer

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

The sentiment behind the attempts we have seen here to discredit the Cowing study seem to stem from two basic premises:

1) There is no problem with the accuracy of laboratory color grading as currently practiced with respect to blue fluorescent diamonds.
2) Blue fluorescent diamonds improve in appearance in typical consumer lighting environments.

Michael’s study challenges both views. He has methodically connected the dots between what modern science has learned about blue fluorescence in diamonds, the content and intensities of light in different devices that have been and/or are currently being used in laboratory grading and in the trade, and the historical concerns about the grading safeguards that should be taken with this unique subset of gem diamonds.

His findings corroborate what other respected gemologists and industry leaders have also found to be true and have published.

Much has been said about his methodology, and I’m sure improvements could be made and additional tests, lighting setups, and graders could be added to the study. But you don’t have to look any further than the GIA study to see the many challenges in any study of this nature, and the assumptions that must be made even when resources for the study are practically unlimited. That does not mean that such a study cannot be a contribution to our understanding or even point up the need for improvements.

The statements of those who have assailed Michael here are heavy on opinion and anecdote, and remarkably light on substance. The argument that typical indoor viewing environments are capable of stimulating whitening due to fluorescence are tied to vague proclamations such a “substantial amount” or “an abundance” of VV in typical light environments. That contradicts what is known about the intensities required to stimulate significant levels of blue fluorescence. The claim that consumers see the benefits of grade whitening in everyday environments itself contradicts the GIA study that concluded that average observers could not make those distinctions.

It’s quite telling that the same folks that vehemently disparage Michael’s work as flawed and invalid, offer little of substance to support their own positions. Because lab color grading is inherently subject to a margin of error it somehow follows that the role of fluorescence as a factor in that error should be ignored?

And why so much vitriol? That’s the hardest thing to understand about some attitudes expressed here. What is so controversial about the idea that labs should be taking precautions to grade the true body color of a diamond? How would suppressing the role of fluorescence and eliminating that as a potential source of error be a disservice to the consumer?
 

Texas Leaguer

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Rockdiamond|1459889592|4015854 said:
Texas Leaguer|1459883898|4015810 said:
sharonp|1459880253|4015782 said:
Texas Leaguer|1459878804|4015767 said:
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.
It seems to me that any level of inaccuracy that could be controlled for in a practical manner, probably should be. The labs have many rigorous processes, carefully vetted masters, extensive grader training, redundant grading, and other safeguards all aimed at accuracy and consistency.

Nobody here in this overly contentious thread is arguing that activated blue fluorescence cannot cause grade whitening] GIA has a long history of teaching/cautioning about it. So, it seems that from a consumer protection perspective, safeguarding the integrity of the color grade would be a continuing priority.

Why does it make sense for GIA to require color masters to be inert, but color grade blue fluorescent stones against them in light capable of stimulating color masking of the diamond being graded?
Bryan, I am inviting you ....please- let's bury the hatchet. Part of the conflict between you and I on this study is the aspect of whitening, and can consumers see this whitening. Based on the post of yours I'm quoting, we seem to agree that it's possible for consumers to see a whitening under certain lighting. Can we agree on this point?

David,
I have no hatchet. If you have one, be my guest to bury it.

If you are unclear on my take on this subject, I invite you to go back and review my postings. It's all there. And I think that others who have been interested enough to endure this thread understand my position pretty well.
 

Rockdiamond

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

HI Bryan- ok- forget about peace and love and burying the hatchet- let's continue in a contentious discussion.
Texas Leaguer|1459889837|4015855 said:
The sentiment behind the attempts we have seen here to discredit the Cowing study seem to stem from two basic premises:

1) There is no problem with the accuracy of laboratory color grading as currently practiced with respect to blue fluorescent diamonds.
2) Blue fluorescent diamonds improve in appearance in typical consumer lighting environments.

Michael’s study challenges both views. He has methodically connected the dots between what modern science has learned about blue fluorescence in diamonds, the content and intensities of light in different devices that have been and/or are currently being used in laboratory grading and in the trade, and the historical concerns about the grading safeguards that should be taken with this unique subset of gem diamonds.

His findings corroborate what other respected gemologists and industry leaders have also found to be true and have published.

Much has been said about his methodology, and I’m sure improvements could be made and additional tests, lighting setups, and graders could be added to the study. But you don’t have to look any further than the GIA study to see the many challenges in any study of this nature, and the assumptions that must be made even when resources for the study are practically unlimited. That does not mean that such a study cannot be a contribution to our understanding or even point up the need for improvements.

The statements of those who have assailed Michael here are heavy on opinion and anecdote, and remarkably light on substance. The argument that typical indoor viewing environments are capable of stimulating whitening due to fluorescence are tied to vague proclamations such a “substantial amount” or “an abundance” of VV in typical light environments. That contradicts what is known about the intensities required to stimulate significant levels of blue fluorescence. The claim that consumers see the benefits of grade whitening in everyday environments itself contradicts the GIA study that concluded that average observers could not make those distinctions.

It’s quite telling that the same folks that vehemently disparage Michael’s work as flawed and invalid, offer little of substance to support their own positions. Because lab color grading is inherently subject to a margin of error it somehow follows that the role of fluorescence as a factor in that error should be ignored?

And why so much vitriol? That’s the hardest thing to understand about some attitudes expressed here. What is so controversial about the idea that labs should be taking precautions to grade the true body color of a diamond? How would suppressing the role of fluorescence and eliminating that as a potential source of error be a disservice to the consumer?

First- you accuse me of misquoting you- yet that's exactly what you're doing here.
I'll pull out and respond to the offending statements you're attributing to me
1) There is no problem with the accuracy of laboratory color grading as currently practiced with respect to blue fluorescent diamonds.
2) Blue fluorescent diamonds improve in appearance in typical consumer lighting environments.
Bryan, Bryan, Bryan- please read the thread.
Garry and I both concur on both these points.
1) Given the physical limitations posed by the diamonds GIA is doing a good job. I never said there's no problem- I said they are doing the best job possible within the physical limitations.
2) If there's enough light for a consumer to accurately determine the color grade of a diamond, a given number of fluoro diamonds whiten. I find it to be true on only some MB/SB's- I am not sure Garry and I agree on that aspect. But we both agree it happens. As do many consumers, and Harry Winston back in the 1970's, where I first observed it and such stones sold at a premium.
Neither Garry or I have made blanket that it ALWAYS occurs.

I'm not interested in challenging Michael, and I'm sorry it came to that. If you had not been flaunting Michael's unsubstantiated opinion as "science" we'd not have had this issue. Once it is brought here, it will need to be looked at with a more critical eye as this is a forum designed for consumers.
His findings corroborate what other respected gemologists and industry leaders have also found to be true and have published.
Please be specific on this.
Who exactly is endorsing this, and when?
Do they have motive to discredit GIA?

The statements of those who have assailed Michael here are heavy on opinion and anecdote, and remarkably light on substance. The argument that typical indoor viewing environments are capable of stimulating whitening due to fluorescence are tied to vague proclamations such a “substantial amount” or “an abundance” of VV in typical light environments.
It is the study itself that is vague on this. Although there's specific light measurments, the environments are never described. The study is making the vague proclamation.
Here's the quote
At usual diamond viewing distances from most artificial overhead consumer lighting those with a UV radiometer and light meter including AGSL and the AGA lighting task force have found around 1uW or less of UV and a lot less than 400fc of visible light intensity. The study showed that in these circumstances there is insufficient UV and VV to stimulate any color improvement from blue fluorescence. Consequently, the true body color (as defined by GIA) is seen.
There's no specific description of the "usual" and "most"- or the particular environment under which these readings were taken. That is the vague part

Why so much vitrol- because this forum acts as a way to debunk incorrect assumptions. I know we've both dedicated a lot of effort to that goal.
 

sharonp

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Rockdiamond|1459884033|4015813 said:
This points out the fact that color and clarity grading is NOT a precise science. And it never will be.
You quoted my post but you don't seem to understand a a single point I made in it. Your diatribe of Michael's work is all I see from this post and that is not worth discussing anymore.
 

michaelgem

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

sharonp|1459875323|4015729 said:
michaelgem|1459873342|4015711 said:
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).
There is so much to say about your posts that by the time a response gets posted, some other issue, question or disagreement has arisen and changed the conversation focus.

No concession is needed in that the 2010 study data confirms that with the prescribed grading practice of maintaining 7" distance (in the vicinity of 30uW of UV) the grade whitening has been reduced to 0-2 grades in all but some VSB's.

The study's 0.63ct VSB marquise, like Tom Tashey's 0.89ct VSB marquise was not an anomaly, as should be clear 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 of around K all the way to D and past to distinctly bluish in natural daylight.

The 2010 study documented the inconsistency in color grading blue fluorescent diamonds in the DiamondDock with its UV and VV allowed to vary over a 2.5 times range. The inconsistency problem was reinforced in recent conversations with Tom Tashey who related that from 2005 - 2008 he acted as Chief Gemological Officer to the World Gemological Institute and a professional consultant to the Israeli Diamond Industry (IDI). He ran studies of the recently arrived new lighting standard DiamondDocks. These studies are like the ones Sharon wishes were included in the 2010 study.

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

That reminded me of a what seemed a questionable statement from GIA Antwerp research gemologist Ron Geurtz. Ron is the developer of the DiamondDock. He told me that the year prior to switching from the DiamondLite to the DiamondDock at the Gem Trade Lab, both light boxes were used together to verify that they yielded the same results.

We appear to have a consensus that GIA was over grading excessively before 2000 using the DiamondLite. Should the consumer now be satisfied with a variable, inconsistent and unknown lesser amount of over grading since 2000 in the DiamondDock?

Although far from mainstream practice some gemologist-appraisers, as part of their appraisal services, offer to grade for the consumer both the true body color (graded in diffused LED lighting) as well as the fluorescence enhanced grade measured at 7 inches in GIA prescribed standard lighting.

If the two measurements were found to be within a grade that would go a long way in restoring trust and confidence in the purchase of a blue fluorescent diamond.
 

pfunk

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

It's unfortunate to see this thread play out the way it has. This is a great opportunity for knowledgable folks to get together and discuss what seems to me to be a very real issue, but unfortunately it has only spun the wheels and gone nowhere.

Seems to me that the evidence shows it is highly likely that some stones are being overgraded as a result of fluorescence. Is the science or methodology perfect? No, probably not but the funding and resources to complete the "perfect" study certainly isn't there for a single person.

No matter whether it happens in most strong blues or only in a few, the fact that it happens at all should be enough to warrant the use of UV filters and/or increased grading distances. Utilizing these things could only act to protect the consumer. No matter whether consumers notice whitening or not, that isn't the point (IMO). Consumer lighting shouldn't be the focus, and utilizing UV filters won't hurt the consumer it seems. Instead, the report would inform the consumer of the worst case scenario and not leave them surprised when their diamond doesn't look as white as it should.

Having said that, if the over grading problem was one that warranted change at the big labs, we would be hearing about more horror stories from consumers.

An interesting topic without a doubt, but unfortunately a lot of hard headed discussion between parties that seemingly refuse to agree with ANYTHING the other side says.
 

Rockdiamond

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Well put pfunk- as usual. You have been the only truly objective participant and I thank you.
We actually all do agree on one aspect though -we all agree that color change in fluoros is possible.
The main difference is that Garry and I are saying that it happens where consumers can see it- and that GIA is able to account for this and grade them. Micheal and Bryan are saying whitening only happens when GIA is grading and that GIA is not able to properly adjust for this.

If a consumer believes Michael's conclusions they will be even less likely to buy a fluoro unless GIA changes their grading procedure and does so publicly
If Garry and I are correct flouros are graded accurately by GIA /AGSL( within a one grade tolerance)
This means they are discounted without good cause and can present a great value.
Readers of this forum are a smart bunch and will obviously make up their own mind.
If this discussion prompts more consumers to go and look for themselves that would be a great thing.
 

Garry H (Cut Nut)

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

I am happy with GIA's new position and I agree with them:
Slide 14 and 15 from the AGA / AGSL report gives GIA's response to the topic:
http://accreditedgemologists.org/lightingtaskforce/Presentation20090204.pdf
“Diamond graders don’t use UV-free lights. John King, GIA Gem Trade Lab’s
director of special projects, explains why. “Yes, you can create an
environment devoid of UV, but it’s a false situation,” he says. “It may
sound like the ideal, but it steps outside the practical world. It’s not relevant
because it doesn’t really exist anywhere. We try to be sensitive to the
practical gemological issues.”
Color Grading “D-Z” Diamonds at the GIA Laboratory – G&G Winter 2008
Requote from: What GIA’s Study Ignored: Jewelers Circular Keystone - Sept 1998

“Moses says GIA continues to study the issue and is mindful of the market.
We don't want to create too rarefied of an environment that other people
would not be able to reproduce," he says. But it's also important, he says,
to remember consumers view diamonds in natural light, which almost
always has UV waves.”

I have also been in the AGSL lab a few times and seen the DiamondDock being used - Peter Yantzer- then director of AGSL was part of the AGA team and AGSL decided to use the DiamondDock color grading methodology.

In reference to the natural light and illumination in my store - customers are more than 8 meters from the plate glass windows and the upper lead light windows (with a wide verandah extending out from them). The slide with data that I have been well aware of for several years clearly shows that the drop off over distance means there will be little or no UV present when my clients are looking at diamonds. But there is lots of light - and this includes VV which clearly is having more influence than people on the other side seem unwilling to admit.

Bryan, you never answered - have you ever seen face up grade whitening in any 'ordinary' places?

_36943.jpg
 

Garry H (Cut Nut)

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

michaelgem|1459905224|4015959 said:
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).


There is so much to say about your posts that by the time a response gets posted, some other issue, question or disagreement has arisen and changed the conversation focus.

No concession is needed in that the 2010 study data confirms that with the prescribed grading practice of maintaining 7" distance (in the vicinity of 30uW of UV) the grade whitening has been reduced to 0-2 grades in all but some VSB's.

The study's 0.63ct VSB marquise, like Tom Tashey's 0.89ct VSB marquise was not an anomaly, as should be clear 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 of around K all the way to D and past to distinctly bluish in natural daylight.

The 2010 study documented the inconsistency in color grading blue fluorescent diamonds in the DiamondDock with its UV and
VV allowed to vary over a 2.5 times range. The inconsistency problem was reinforced in recent conversations with Tom Tashey who related that from 2005 - 2008 he acted as Chief Gemological Officer to the World Gemological Institute and a professional consultant to the Israeli Diamond Industry (IDI). He ran studies of the recently arrived new lighting standard DiamondDocks. These studies are like the ones Sharon wishes were included in the 2010 study.

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

That reminded me of a what seemed a questionable statement from GIA Antwerp research gemologist Ron Geurtz. Ron is the developer of the DiamondDock. He told me that the year prior to switching from the DiamondLite to the DiamondDock at the Gem Trade Lab, both light boxes were used together to verify that they yielded the same results.

We appear to have a consensus that GIA was over grading excessively before 2000 using the DiamondLite. Should the consumer now be satisfied with a variable, inconsistent and unknown lesser amount of over grading since 2000 in the DiamondDock?

Although far from mainstream practice some gemologist-appraisers, as part of their appraisal services, offer to grade for the consumer both the true body color (graded in diffused LED lighting) as well as the fluorescence enhanced grade measured at 7 inches in GIA prescribed standard lighting.

If the two measurements were found to be within a grade that would go a long way in restoring trust and confidence in the purchase of a blue fluorescent diamond.
[/quote]

Michael can you present evidence of this VV variance?
 

Texas Leaguer

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Garry,
I will admit that your theory that there is sufficient VV to activate whitening levels of blue fluoro in typical consumer environments is intriguing, as I said earlier in the conversation. However, I have not seen any evidence presented here to convince me that this more than a convenient assumption. Since that notion seems to be contradicted by the process documented for UV, and since intensity requirements appear to be the similar for both UV and VV in terms of the ability to stimulate blue fluorescence, it does not seem logical to me that VV would be capable of the appearance changes that you are suggesting, outside of unusually bright light (non-typical consumer lighting).

And to the question you keep asking me, I really don't think that what I have seen or not seen or think I have seen in my 40 year career, will settle anything here. As you know, I am now on record as skeptical of the idea, which was considered common knowledge for most of my career and continues to this day, that whitening due to fluorescence is a benefit that consumers experience on a regular basis. I see whitening under conditions known to stimulate fluoro - direct sunlight and viewing very close to fluoro bulbs - but that is something on which we all agree and it is consistent with what the science predicts.
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Garry H (Cut Nut)|1459923369|4016036 said:
michaelgem|1459905224|4015959 said:
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).


There is so much to say about your posts that by the time a response gets posted, some other issue, question or disagreement has arisen and changed the conversation focus.

No concession is needed in that the 2010 study data confirms that with the prescribed grading practice of maintaining 7" distance (in the vicinity of 30uW of UV) the grade whitening has been reduced to 0-2 grades in all but some VSB's.

The study's 0.63ct VSB marquise, like Tom Tashey's 0.89ct VSB marquise was not an anomaly, as should be clear 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 of around K all the way to D and past to distinctly bluish in natural daylight.

The 2010 study documented the inconsistency in color grading blue fluorescent diamonds in the DiamondDock with its UV and
VV allowed to vary over a 2.5 times range. The inconsistency problem was reinforced in recent conversations with Tom Tashey who related that from 2005 - 2008 he acted as Chief Gemological Officer to the World Gemological Institute and a professional consultant to the Israeli Diamond Industry (IDI). He ran studies of the recently arrived new lighting standard DiamondDocks. These studies are like the ones Sharon wishes were included in the 2010 study.

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

That reminded me of a what seemed a questionable statement from GIA Antwerp research gemologist Ron Geurtz. Ron is the developer of the DiamondDock. He told me that the year prior to switching from the DiamondLite to the DiamondDock at the Gem Trade Lab, both light boxes were used together to verify that they yielded the same results.

We appear to have a consensus that GIA was over grading excessively before 2000 using the DiamondLite. Should the consumer now be satisfied with a variable, inconsistent and unknown lesser amount of over grading since 2000 in the DiamondDock?

Although far from mainstream practice some gemologist-appraisers, as part of their appraisal services, offer to grade for the consumer both the true body color (graded in diffused LED lighting) as well as the fluorescence enhanced grade measured at 7 inches in GIA prescribed standard lighting.

If the two measurements were found to be within a grade that would go a long way in restoring trust and confidence in the purchase of a blue fluorescent diamond.


Michael can you present evidence of this VV variance?
Garry, as to your question that I bolded directly above, I think that is reference to the wide range of light intensity in the stated specs for the DiamondDock (bullet point #2):

DiamondDock lighting were given by King et al. (2008), and include:
• Stable, fluorescent lamps 17 in. (43cm) or longer
• An intensity of light in the range of 2000–4500 lux at the surface of the
grading tray
• An 8–10 in. distance between the lamps and the grading tray
• A colour spectrum close to CIE D55-D65
• A colour temperature between 5500 K and 6500 K
• A colour rendering index of 90 or above
• No noticeable output in the short- or medium-wave UV range (or a filter available to eliminate UV in this range)
• An emission for long-wave UV (between 315 and 400 nm, close to the reference spectrum of D55-D65)
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Texas Leaguer|1459947204|4016103 said:
Garry H (Cut Nut)|1459923369|4016036 said:
michaelgem|1459905224|4015959 said:
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).


There is so much to say about your posts that by the time a response gets posted, some other issue, question or disagreement has arisen and changed the conversation focus.

No concession is needed in that the 2010 study data confirms that with the prescribed grading practice of maintaining 7" distance (in the vicinity of 30uW of UV) the grade whitening has been reduced to 0-2 grades in all but some VSB's.

The study's 0.63ct VSB marquise, like Tom Tashey's 0.89ct VSB marquise was not an anomaly, as should be clear 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 of around K all the way to D and past to distinctly bluish in natural daylight.

The 2010 study documented the inconsistency in color grading blue fluorescent diamonds in the DiamondDock with its UV and
VV allowed to vary over a 2.5 times range. The inconsistency problem was reinforced in recent conversations with Tom Tashey who related that from 2005 - 2008 he acted as Chief Gemological Officer to the World Gemological Institute and a professional consultant to the Israeli Diamond Industry (IDI). He ran studies of the recently arrived new lighting standard DiamondDocks. These studies are like the ones Sharon wishes were included in the 2010 study.

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

That reminded me of a what seemed a questionable statement from GIA Antwerp research gemologist Ron Geurtz. Ron is the developer of the DiamondDock. He told me that the year prior to switching from the DiamondLite to the DiamondDock at the Gem Trade Lab, both light boxes were used together to verify that they yielded the same results.

We appear to have a consensus that GIA was over grading excessively before 2000 using the DiamondLite. Should the consumer now be satisfied with a variable, inconsistent and unknown lesser amount of over grading since 2000 in the DiamondDock?

Although far from mainstream practice some gemologist-appraisers, as part of their appraisal services, offer to grade for the consumer both the true body color (graded in diffused LED lighting) as well as the fluorescence enhanced grade measured at 7 inches in GIA prescribed standard lighting.

If the two measurements were found to be within a grade that would go a long way in restoring trust and confidence in the purchase of a blue fluorescent diamond.


Michael can you present evidence of this VV variance?
Garry, as to your question that I bolded directly above, I think that is reference to the wide range of light intensity in the stated specs for the DiamondDock (bullet point #2):

DiamondDock lighting were given by King et al. (2008), and include:
• Stable, fluorescent lamps 17 in. (43cm) or longer
• An intensity of light in the range of 2000–4500 lux at the surface of the
grading tray

• An 8–10 in. distance between the lamps and the grading tray
• A colour spectrum close to CIE D55-D65
• A colour temperature between 5500 K and 6500 K
• A colour rendering index of 90 or above
• No noticeable output in the short- or medium-wave UV range (or a filter available to eliminate UV in this range)
• An emission for long-wave UV (between 315 and 400 nm, close to the reference spectrum of D55-D65)
Right, Bryan,

The DiamondDock lighting specifications allow • An intensity of light in the range of 2000–4500 lux at the surface of the grading tray

For those who have not read the full article, in The Journal of Gemmology/ 2010 / Volume 32 / No. 1–4 at:
http://www.acagemlab.com/temp/CowingOvergrading.pdf

Here is the DiamondDock story:

2. GIA DiamondDock

In 2000 the GIA discontinued the manufacture and use of the DiamondLite and replaced it with the DiamondDock, which employs two 17 in. F15T8VLX Verilux full spectrum fluorescent tubes. Diamonds are graded on a white tray placed on the DiamondDock shelf, which means that there is a 7 in. grading distance from the light tubes (see discussion below).

The basic technical specifications of the DiamondDock lighting were given by King et al. (2008), and include:
• Stable, fluorescent lamps 17 in. (43cm) or longer
• An intensity of light in the range of 2000–4500 lux at the surface of the grading tray
• An 8–10 in. distance between the lamps and the grading tray
• A colour spectrum close to CIE D55-D65
• A colour temperature between 5500 K and 6500 K
• A colour rendering index of 90 or above
• No noticeable output in the short- or medium-wave UV range (or a filter available to eliminate UV in this range)
An emission for long-wave UV (between 315 and 400 nm, close to the reference spectrum of D55-D65)

The twin F15T8VLX fluorescent tubes or their equivalent is the standard lighting spelled out in the basic technical specifications for D-to-Z colour grading. (G&G, winter 2008). Although a grading distance of 8-10 inches is specified, the shelf of the DiamondDock enforces a 7 inch grading distance from lamps to grading tray.

The exact distance is important to establish, because it in essence defines the chosen “standard” amount of UV and VV.
GIA researcher Ronald Geurtz (pers. com.) explained: “With the distance between shelf and the center of the bulb at 8-10 inches, the distance between the diamond and the surface of the bulb is around 7 inches.”

He notes an important point about this current lighting standard. The allowed range of light intensity of 2000-4500lux at the surface of the grading tray means the “standard” amount of UV and VV is also allowed to vary over the same 2.25 times range.

Such an large allowed variation of UV and VV defeats standardization of the amount of fluorescence stimulation in blue fluorescent diamonds. Even though lessened by the change from the DiamondLite, the post 2000 GIA requirement for long wave UV in the DiamondDock results in variable, inconsistent and unknown amounts of over grading.

Wouldn't the consumer be better served by grading for the diamond's true color, which was the goal advocated by founder Shipley and pre-2000 GIA teaching?
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Garry H (Cut Nut)|1459923369|4016036 said:
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).
Add 2 grades whitening(which grades? see below) to the expected grading accuracy between graders of 1 grade and you can quickly hit 3-4 grades off.
3 grades in higher colors where whitening is more likely to move a grade is a huge amount of money.

The same amount of whitening to move a g to an e would barely move a ijk in all but marginal cases.
The amount to move an e to f would not even register on the color scale at j.
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

michaelgem|1459961663|4016200 said:
Wouldn't the consumer be better served by grading for the diamond's true color, which was the goal advocated by founder Shipley and pre-2000 GIA teaching?
yes they would
 

Rockdiamond

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Let's look at the evidence that's been presented so far:
1) Michael says GIA is overgrading.
No other trade member participating here, except Bryan, is finding this a valid claim.
Plus, if there was an issue, many other people ( including Garry and I) would be making noise about it.
Michael has published a study to back up his claim.
I have my own study- I have personally bought over 20 million dollars of diamonds over the past few years and I specifically look for fluoros. I have inspected far more than I've bought. We're talking massive numbers of stones.
I am also published and far more widely read by consumers than Michael ( heavy web traffic).
These are stones which are extensively photographed on our site- and many have been sold to consumers- many PS members.
I'm starting very plainly (again)- no overgrading problem exists.
The issue of a single grader- who has his own lab to promote ( Michael) is also there.
Readers can choose to believe what they want.

2) whitening- This is less of an issue but Bryan's answers are almost comical. It does not matter if he's seen it or not ( he won't say) because the study suggests....
I've posted pics illustrating it.
Let's go back to this study to see what it says......
Carry on y'all

ETA-one of our brokers just brought by an SB L color.
The change of hue was startling.
I could not get it to look darker than L, but in any sort of bright lighting ( which includes indirect sun) the stone goes up to maybe...G??

Very cool stone, and I bought it.
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Rockdiamond|1459965402|4016231 said:
Let's look at the evidence that's been presented so far:
1) Michael says GIA is overgrading.
No other trade member participating here, except Bryan, is finding this a valid claim.
I find it plausible but not proven beyond doubt as gia currently grades.
Using the older tubes I am convinced there was an issue and had been for a long time based on Marty's posts years ago.
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

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

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Rockdiamond|1459968188|4016251 said:
GIA graded diamonds were exponentially less popular prior to 2000.
It's rare to find a cert that old on the market today to use for comparison- but it's really not relevant to GIA's current practice.
Again to point out- we don't know exactly how GIA is doing it- but we do know they produce very consistent color grades.
Given that I understand how difficult that is to do, I believe GIA is using procedures which make the whole distance from the bulb discussion irrelevant.
The gemologist-appraiser community is periodically given graduate course updates on GTL grading held at GIA that include observation of grading in the lab. With their 2008 article "Color grading “D-to-Z” diamonds at the GIA Laboratory" and these in house graduate seminars GIA has been transparent on "exactly how GIA is doing it"

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

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

michaelgem|1459970528|4016279 said:
Rockdiamond|1459968188|4016251 said:
GIA graded diamonds were exponentially less popular prior to 2000.
It's rare to find a cert that old on the market today to use for comparison- but it's really not relevant to GIA's current practice.
Again to point out- we don't know exactly how GIA is doing it- but we do know they produce very consistent color grades.
Given that I understand how difficult that is to do, I believe GIA is using procedures which make the whole distance from the bulb discussion irrelevant.
The gemologist-appraiser community is periodically given graduate course updates on GTL grading held at GIA that include observation of grading in the lab. With their 2008 article "Color grading “D-to-Z” diamonds at the GIA Laboratory" and these in house graduate seminars GIA has been transparent on "exactly how GIA is doing it"

There is only one way to "make the whole distance from the bulb discussion irrelevant." That is by grading for the true color in lighting that does not stimulate grade whitening fluorescence. That is accomplished either by grading in diffused LED lighting, or UV filtered and diffused fluorescent lighting.
I'm very honored that you finally responded to something I've written Michael- thank you.
Have you witnessed GIA color grading procedures?
If so, when?
How many graders look at the stone?
Are they given an opportunity to look a the stone under any other lighting than the dock?
 

michaelgem

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

ETA-one of our brokers just brought by an SB L color.
The change of hue was startling.
I could not get it to look darker than L, but in any sort of bright lighting ( which includes indirect sun) the stone goes up to maybe...G??

Very cool stone, and I bought it.

David,

With stones like this, and your color grading ability, you are well equipped to carry on this data collection and study of blue fluorescent diamonds.

You undoubtedly have a two tube fluorescent light swing arm desk lamp. Try grading that SB L at 7 inches under the lamp to see if that DiamondDock prescribed lighting agrees with GIA's L call. Then stick it up close to the tubes like was done in the DiamondLite at GIA prior to 2000.

If you wanted to go all in you could buy Dazor's Lumilus LED Desk Base Light (31") ( https://www.dazor.com/store/Desk-Base-Light-31-LED.html) and Dazor's UV radiometer and light meter kit (https://www.dazor.com/store/search.php?mode=search&page=1&keep_https=yes). That way you can check to see if the true color is any lower than L. With the meters you can document like the 2010 study did the amounts of UV and visible light energy present at the diamond in each of these circumstances.

That's the equipment I'm getting for a San Diego diamond wholesaler, who wants to guage diamond's true color. Coincidentally, he also just acquired a GIA graded SB and wants to know its true color. Its graded a D and he is hoping it is a true blue-white that does not drop below E in the LED lighting.

Your SB L color acquisition is very interesting since the five grades of improvement would not be expected in a SB, only a VSB.
 

Rockdiamond

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

YES!!!!!
Excellent idea and new direction to a difficult discussion- thank you Michael!
I would be an excited and willing participant in a new study Michael.
Yes, I have the two ( actually it's 3 bulbs, but only two are connected) bulb lamp with swing arm.
I like the Dazor lamp you linked to. I will obtain one.
I'd try to borrow a light meter- if need be and we're getting serious, I'd buy the Dazor ( $350)



I will look again at the new L color stone tomorrow with fresh eyes.
I have found that it's useless to try and grade color after looking at screens, diamonds, people, etc for more than 5 hours or so- I need fresh eyes to really see the finest differences
Plus I won't ever buy a stone without looking in natural lighting which includes sunlight- preferably between noon and 4 pm at this time of year.

I think discussion of the details on how to accurately assess the color is an important aspect for anyone truly interested in color grading.
The entire section of the debate about GIA grading procedures for example.
I have not had the opportunity to see them do it- and not even taken all that much time reading the published literature.
I have asked them directly- and gotten incomplete answers.
So I am basing my opinion on the resultant grades I see- and they are very good.
Extrapolating from my own experience, it seems to me that they are probably machine grading the smaller, and easier stones.
Conversely, on complicated and important stones, it's my belief that multiple graders confer- and that they will look at the stone in multiple lighting environments.
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Texas Leaguer|1459946050|4016095 said:
Garry,
I will admit that your theory that there is sufficient VV to activate whitening levels of blue fluoro in typical consumer environments is intriguing, as I said earlier in the conversation. However, I have not seen any evidence presented here to convince me that this more than a convenient assumption. Since that notion seems to be contradicted by the process documented for UV, and since intensity requirements appear to be the similar for both UV and VV in terms of the ability to stimulate blue fluorescence, it does not seem logical to me that VV would be capable of the appearance changes that you are suggesting, outside of unusually bright light (non-typical consumer lighting).

And to the question you keep asking me, I really don't think that what I have seen or not seen or think I have seen in my 40 year career, will settle anything here. As you know, I am now on record as skeptical of the idea, which was considered common knowledge for most of my career and continues to this day, that whitening due to fluorescence is a benefit that consumers experience on a regular basis. I see whitening under conditions known to stimulate fluoro - direct sunlight and viewing very close to fluoro bulbs - but that is something on which we all agree and it is consistent with what the science predicts.
Bryan in less time than it took to write your reply you could have taken 2 stones from inventory and walked around looking at them.
If you won't do that, can you tell me why please?
I really do not understand.
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Garry H (Cut Nut)|1459978136|4016333 said:
Texas Leaguer|1459946050|4016095 said:
Garry,
I will admit that your theory that there is sufficient VV to activate whitening levels of blue fluoro in typical consumer environments is intriguing, as I said earlier in the conversation. However, I have not seen any evidence presented here to convince me that this more than a convenient assumption. Since that notion seems to be contradicted by the process documented for UV, and since intensity requirements appear to be the similar for both UV and VV in terms of the ability to stimulate blue fluorescence, it does not seem logical to me that VV would be capable of the appearance changes that you are suggesting, outside of unusually bright light (non-typical consumer lighting).

And to the question you keep asking me, I really don't think that what I have seen or not seen or think I have seen in my 40 year career, will settle anything here. As you know, I am now on record as skeptical of the idea, which was considered common knowledge for most of my career and continues to this day, that whitening due to fluorescence is a benefit that consumers experience on a regular basis. I see whitening under conditions known to stimulate fluoro - direct sunlight and viewing very close to fluoro bulbs - but that is something on which we all agree and it is consistent with what the science predicts.
Bryan in less time than it took to write your reply you could have taken 2 stones from inventory and walked around looking at them.
If you won't do that, can you tell me why please?
I really do not understand.
Garry,
As I stated earlier, I am happy to run any simple evaluations on any stones that anyone here cares to send me and report back my observations. Just give me a heads up so I can alert our shipping department.
 

Garry H (Cut Nut)

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Texas Leaguer|1459979662|4016344 said:
Garry H (Cut Nut)|1459978136|4016333 said:
Texas Leaguer|1459946050|4016095 said:
Garry,
I will admit that your theory that there is sufficient VV to activate whitening levels of blue fluoro in typical consumer environments is intriguing, as I said earlier in the conversation. However, I have not seen any evidence presented here to convince me that this more than a convenient assumption. Since that notion seems to be contradicted by the process documented for UV, and since intensity requirements appear to be the similar for both UV and VV in terms of the ability to stimulate blue fluorescence, it does not seem logical to me that VV would be capable of the appearance changes that you are suggesting, outside of unusually bright light (non-typical consumer lighting).

And to the question you keep asking me, I really don't think that what I have seen or not seen or think I have seen in my 40 year career, will settle anything here. As you know, I am now on record as skeptical of the idea, which was considered common knowledge for most of my career and continues to this day, that whitening due to fluorescence is a benefit that consumers experience on a regular basis. I see whitening under conditions known to stimulate fluoro - direct sunlight and viewing very close to fluoro bulbs - but that is something on which we all agree and it is consistent with what the science predicts.
Bryan in less time than it took to write your reply you could have taken 2 stones from inventory and walked around looking at them.
If you won't do that, can you tell me why please?
I really do not understand.
Garry,
As I stated earlier, I am happy to run any simple evaluations on any stones that anyone here cares to send me and report back my observations. Just give me a heads up so I can alert our shipping department.
So how many stones do you have access to at work Bryan? I really do not understand your reticence?
 

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Garry H (Cut Nut)|1459981713|4016353 said:
Texas Leaguer|1459979662|4016344 said:
Garry H (Cut Nut)|1459978136|4016333 said:
Texas Leaguer|1459946050|4016095 said:
Garry,
I will admit that your theory that there is sufficient VV to activate whitening levels of blue fluoro in typical consumer environments is intriguing, as I said earlier in the conversation. However, I have not seen any evidence presented here to convince me that this more than a convenient assumption. Since that notion seems to be contradicted by the process documented for UV, and since intensity requirements appear to be the similar for both UV and VV in terms of the ability to stimulate blue fluorescence, it does not seem logical to me that VV would be capable of the appearance changes that you are suggesting, outside of unusually bright light (non-typical consumer lighting).

And to the question you keep asking me, I really don't think that what I have seen or not seen or think I have seen in my 40 year career, will settle anything here. As you know, I am now on record as skeptical of the idea, which was considered common knowledge for most of my career and continues to this day, that whitening due to fluorescence is a benefit that consumers experience on a regular basis. I see whitening under conditions known to stimulate fluoro - direct sunlight and viewing very close to fluoro bulbs - but that is something on which we all agree and it is consistent with what the science predicts.
Bryan in less time than it took to write your reply you could have taken 2 stones from inventory and walked around looking at them.
If you won't do that, can you tell me why please?
I really do not understand.
Garry,
As I stated earlier, I am happy to run any simple evaluations on any stones that anyone here cares to send me and report back my observations. Just give me a heads up so I can alert our shipping department.
So how many stones do you have access to at work Bryan? I really do not understand your reticence?
A lot. But what is the point of different observers looking at different stones? I don't see how that would advance the discussion.
 

Rockdiamond

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Re: Article: Over Grading of Blue Fluorescent Diamonds Revis

Bryan, this is such a win win- I don't get your reluctance.
If you sample a bunch of SB stones in H-L colors you'll find one or more that lighten up a bit- whiten.

Once you do that, your own observation is all we need.
No corroboration.

Do you have good color vision?

If you do see what we're all are insisting actually exists, you'll simply realize that stones in this category are more attractive for your clients.
As it stands, your position would make it seem like you don't think your clients should buy MB/SB's because you believe they are misgraded- and then even if they're not, you're denying that some of these beauties actually benefit from having MB/SB.
Seems like the opposite of a win win- for you.
 
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