Should we discourage or recommend FL stones?

[OoohShiny]

Another of the same stones, this time with a accurately graded G Master to the left and right in my gem room with only LED overhead lighting (I have replaced the UV tubes with LED's last year because I have a green tinge).

I'm pretty colour-sensitive in real life and have correctly sorted a D, E and F in a retail shop environment before (pre-PS!) but I swear that all these stones in the picture look identical...

 

[Garry H (Cut Nut)]

I'm pretty colour-sensitive in real life and have correctly sorted a D, E and F in a retail shop environment before (pre-PS!) but I swear that all these stones in the picture look identical...

I agree. I can see a little more than you can in the photo (latest samsung with macro lens).
Every time I try to take a grading lamp photo I get yellow bands across the field of view - so I will need to get out the real camera.

 

[Karl_K]

I agree. I can see a little more than you can in the photo (latest samsung with macro lens).
Every time I try to take a grading lamp photo I get yellow bands across the field of view - so I will need to get out the real camera.

I am more interested in hearing what you are seeing in person when taking them.

 

[Garry H (Cut Nut)]

I am more interested in hearing what you are seeing in person when taking them.

Face up - Sitting at my desk with the blinds closed and only the overhead single fluor light (replaced with LED tube) i cant see any face up colour - just dark sparkly diamonds.
Face up at the window blinds opened at 5.00pm (4pm minus daylight saving) on a cloudy day the G stg blue is better than the E (it feels better, maybe 1/2 a grade).

Table down at desk - only difference is the E SI2 is a little grey because of the inclusions.
At the window, the G is clearly better color.

Walking around into various rooms with some south daylight (Sun is currently in the North West in Australia at 5.20pm) I can just make out the G is a lower color face down in 1 of 10 viewing situations. 1M - 3ft from a south facing wind the G clearly wins face down. In the other 9 places I have not enough light to know if they were K or D.

I would love others to try this please. It is not science - it is opinion. And people will challenge my opinion. So Karl, it is not my preferred method.
I am charging my brand new Olympus Tough camera with a piece of white card mounted over the front.

 

[Venzen007]

With all that you've described, Gary, I have to wonder how it was given a grade of G to begin with.

 

[Garry H (Cut Nut)]

With all that you've described, Gary, I have to wonder how it was given a grade of G to begin with.

It looks G in the grading light, but I can not get a photo because the mercury vapour strobing and the phone always captures a yellow band. See how the right side is all tinted yellow V007.
This is an attempt to show a G master CZ on the left, E centre and G stg blue on the right

 

[Venzen007]

My concern, then, is the relevance of the "grading light" to real world lighting situations.

 

[Karl_K]

My concern, then, is the relevance of the "grading light" to real world lighting situations.

It is really impossible to pick one lighting that is representative of the real world.
At any given moment any diamond someone is wearing will be "seeing" multiple light sources not one.

 

[Karl_K]

Interesting Garry I will have to consider that when im more awake.

 

[Venzen007]

It is really impossible to pick one lighting that is representative of the real world.

Then what good is it? If the standard has little correlation to real world lighting environments, just the fact that it is standardized isn't useful. For example, would it make sense to determine and grade the reactivity of gems based on how well they hold up to a specific chemical they'll never see outside the lab?

At any given moment any diamond someone is wearing will be "seeing" multiple light sources not one.

Then why not set up a grading environment based on that? I'm sure GIA is sophisticated enough to consider color over multiple lighting environments or typical mixed light situations.

If GIA grades two stones as a G and and E, yet there are several common situations where the E will appear less "white", that's a problem, especially when the price/value of stones is so affected.

 

[sledge]

This was my point earlier @Venzen007.

What we seem to know about fluor is that it behaves as it wishes based on the intensity of fluor and intensity of the UV it's exposed to.

If stones with no fluor are being graded amongst stones with fluor, you need to remove the UV element so the lab is able to report color as accurately as possible regardless of fluor levels.

Then if a stone is graded D, E or G we know that's the true color. If it improves because of the fluor and right/specific conditions, then great, that's a bonus. But allowing UV to potentially provide a false grade of any magnitude is a mistake IMO.

It's my belief, the only reason to not do this is to protect the value and grading already in place.

 

[Venzen007]

It's my belief, the only reason to not do this is to protect the value and grading already in place.

I was thinking about this as I posted that last post, and I suspect altering how color is graded, if warranted, would need to be considered very carefully so as not to undo or call into question all of the stones previously graded. I don't see them doing it for fear of undermining their own authority or at least giving the impression of.

We know good science isn't afraid to make corrections/adjustments no matter how entrenched the previous understanding or way of doing it, but I suspect GIA and the like are in the diamond business first and the science business second, if at all.

 

[Karl_K]

A ton of things in the trade are done that way because that's the way it was done before.
The reason there is a standard is to allow people all over the world to grade diamonds with relatively inexpensive equipment using their gia training.

GIA Diamond Dock®

The new GIA DiamondDock® integrates years of GIA lighting research into standard daylight conditions for D-Z diamond color grading and cut evaluation supplemented with customized LED illumination to provide the proper viewing environment for additional aspects of cut evaluation. Integrates GIA...

store.gia.edu

 

[Venzen007]

From their description of their equipment:

- "integrates years of GIA lighting research"
- "provide(s) the proper viewing environment"
- "features...correct lighting to neutralize and minimize ambient conditions.
- "optimal lighting for assessing and demonstrating to customers, the cut quality and color of different diamonds

The claim is that the lighting environment created by this dock is "proper, correct, and optimal". Well, proper, correct, and optimal for what purpose, and on what do they based their use of these adjectives. Admittedly, I haven't read the "years of GIA lighting research", and maybe that would answer all my questions or maybe it would just raise more.

Do ya'll feel these adjectives are warranted?

 

[sledge]

Look back at my post #171 where I screen capped a copy of the Cowing report that indicated a changed from the GIA DiamondLite to the DiamondDock increased the distance of the bulbs from 2-3" away to about 7" away.

That small change lowered the UV intensity, which Cowing states altered the effect in color grading.

There is also a blurb in the report that using a filter doesn't effect color but completely removes UV, and that possibly increasing the distance may have a similar effect.

That's the thing I don't get -- GIA kind of half fixed the problem.

 

[Karl_K]

They also changed the tube used:

Tube for GIA DiamondLite Model 180000 - Fluorescent 6 Watt [white]

Tube for GIA DiamondLite Model 180000 - Fluorescent 6 Watt [white] - 9' Length' - ANSI code is F6T5/D Usually ships in 1 business day. SKU: 592000

store.gia.edu

Tube for GIA DiamondDock -15 Watt Fluorescent

store.gia.edu

The industry is to small for them to have custom tubes made so they have to use what they can get.
That led to many of the issues.
The tube for the DiamondLite has changed brands and spectrum many times over the years. The UV component has varied greatly.

 

[Rockdiamond]

Guys- you're trying to fit a round peg into a square hole here.
GIA is forced to make compromises to issue color grades- one way or the other. There will never be a set "answer" to this debate.
There's never going to be "science" that changes the basic facts- @Karl_K stated it well.
A diamond changes color based on its surroundings, as well as the intensity and nature of the lighting source(s).
Diamonds of any color will do this.
Some fluorescent diamonds exhibit exaggerated changes based on lighting.
Nothing we say or do is going to change that.

At Harry Winston, the grading method was a practical one- GIA reports were not prominent, so nicer looking stones sold for more.
I took that approach into my own professional outlook. GIA can say whatever they want, if a diamond looks better- or worse- than it's color grade, the buyer will get an advantage, or the stone is harder to sell.
To me, it's not about tradition or the way it's always been done- it's about what is practical in buying and selling from day to day.

Cowing will not defend or even discuss his "work"- continuing to dredge it up seems to be truly detrimental to those who actually want to learn.

I appreciate Garry's attempts to illustrate with photos- but the subtle differences are so subtle that a fair percentage of observers won't be able to detect one or two shades difference no matter the lighting.

 

[Texas Leaguer]

This was my point earlier @Venzen007.

What we seem to know about fluor is that it behaves as it wishes based on the intensity of fluor and intensity of the UV it's exposed to.

If stones with no fluor are being graded amongst stones with fluor, you need to remove the UV element so the lab is able to report color as accurately as possible regardless of fluor levels.

Then if a stone is graded D, E or G we know that's the true color. If it improves because of the fluor and right/specific conditions, then great, that's a bonus. But allowing UV to potentially provide a false grade of any magnitude is a mistake IMO.

It's my belief, the only reason to not do this is to protect the value and grading already in place.

@sledge,
This is precisely the issue that Cowing et al set out to document. @Venzen007 The historical teachings of GIA are chronicled in the article. It is also the issue that Martin Rapaport wrote his missive to the trade about in terms of getting back to grading 'true' color. And both Cowing and Rapaport argue that fluoresce would be more likely to be seen by the market as a positive feature if grading practices were returned to the original philosophy of eliminating grade whitening fluorescence by filtering out UV and/or grading at distances from the source that do not have enough intensity to stimulate grade whitening fluorescence.

I believe GIA did get the message and labs are more aware of this potential issue today, and I believe with that awareness have come better practices. But GIA had to sort of thread the needle by transitioning their message about lighting in the grading environment while not directly acknowledging possible overgrading. In order to accomplish that they kind of did away with the imperative contained in the original teachings.

It is important to understand that GIA has a HUGE global constituency who are very traditional and quite status quo oriented. As such GIA are very careful not to cause controversy that could negatively impact manufacturers. This is why it took GIA 10 years to come out with a cut grade after AGS demonstrated the demand for it. And why it is a very forgiving grading system. They have not come out with a grading system for fancies, at least in part, for the same reasons.

While manufacturers would greatly benefit from more acceptance of fluorescence, at this point the stigma might be pretty well baked in to the market. This is why you see so much promotion of the supposed benefits of whitening in normal viewing environments, with proponents of this benefit so dug in.

 

[Texas Leaguer]

Cowing will not defend or even discuss his "work"- continuing to dredge it up seems to be truly detrimental to those who actually want to learn.

This is a patently false statement - as anyone who has read the original thread will quickly realize.

Article - Over Grading of Blue Fluorescent Diamonds Revisited

Michael Cowing from Accredited Gemologist Association (AGA) Certified Gem Laboratory has put together an article about blue fluorescent diamond over grading. https://www.pricescope.com/journal/blue-fluorescent-diamonds-color-grading-issues Thank you Michael.

www.pricescope.com

 

[Rockdiamond]

Not much ( or anything) settled in that monster of a thread. I have not delved back into it for a while- I just spent a little while reading...I stand corrected, Michael did participate more than I remembered.
However, nothing was settled at all. And Micheel ultimately could not defend some very crucial aspects of the paper- such as methodology of grading- among many other issues..
Garry and I have one position, that the study was not useful for consumers.
@Texas Leaguer -You feel the paper proves something and it's useful to consumers.
Clearly you're free to tell your clients whatever you want.
IN a public discussion, questions will be raised. That is how education takes place.

 

[Texas Leaguer]

IN a public discussion, questions will be raised. That is how education takes place.

Making statements which you know to be false in order to cast doubt on an opposing viewpoint is NOT how education takes place. That is how gaslighting takes place.

 

[Rockdiamond]

That is how gaslighting takes place.

Do you mean like claiming something is scientifically proven, when clearly, it's not?
What exactly am I saying which is knowingly false???

 

[Rockdiamond]

I started this thread because the subject is quite interesting- to both readers and shoppers.
My answer to the question I posed ( should we recommend, or discourage fl stones?) is- yes, and or no. Depending on the buyer and the diamond.
Some fluorescent diamonds behave in a manner that makes them near impossible to color grade. For some buyers, that aspect is an issue. Other buyers, not so much.
If a company excludes fluorescent diamonds from its brand, it makes a lot of sense that such a company does not see value in them. I totally get this, as we avoid buying fluorescent yellow diamonds because they raise questions- but I will gladly discuss- or obtain them for clients who want them. I personally adore many blue stones in the colorless and near-colorless- and they trade at large discounts- so I'm always interested as a buyer. Many people love them too.
If a company is trying to "push" fluorescent diamonds, that's another red flag, to me. Educate, rather than push one way or the other- is how we do it.


I welcome discussing fluorescent diamonds- it's a lot better than discussing ...well, other things nowadays.
If only the biggest disputes in the world were about fluorescent diamonds, we'd all be a lot happier. I have no desire to clash with Bryan- and honestly- I started the thread in a discussion based on my experience- so all the contention is misplaced,
Peace Bryan- we can both have opinions that differ.

 

[Garry H (Cut Nut)]

EDIT: Please read this article before discussing my points below.
https://www.gia.edu/doc/Coloring-Grading-D-to-Z-Diamonds-at-the-GIA-Laboratory.pdf
Anyone who makes a statement that is refuted by GIA totally coming clean about their previous mistakes needs to know they did listen and did change their previous bad color grading methods.

A few things about the several comments.
1. GIA made 2 changes that did result in a radical change to almost all pre 2000 color grades for blue fluorescent diamonds. For example the 4 grade drops in filtered UV would possibly get a 3 grade drop in todays GIA environment. Cowing notes this reduced the UV output to about one quarter (but he used the wrong measuring instrument and measured the wrong radiation frequencies).
2. In one GIA article - I can not remember which one - but from early 2000's the mention using CIE indoor ID65 as a standard they set to achieve with the new Diamond Dock.
3. Diamond Dock was originally built as a part of the need for a portable cut quality survey and was repurposed as a color grading environment. (Sergey and I have made many criticisms of the use of this box for cut grading).
4. I have raised several issues about Cowing's articles as in the past year or two I have learned a lot more information and identified flaws in that work. Mainly he did not really account for the changes in GIA's grading lighting, he used the wrong measuring Solarmeter, and did not properly account for violet and near violet effects which are common radiations all around us and have a much stronger effect than the previously considered much shorter wave length UV lights.

Happy to discuss any one of the above 4 points until we get some consensus.
Or any other individual fact or variant.

 

[sledge]

Guys- you're trying to fit a round peg into a square hole here.
GIA is forced to make compromises to issue color grades- one way or the other. There will never be a set "answer" to this debate.
There's never going to be "science" that changes the basic facts- @Karl_K stated it well.
A diamond changes color based on its surroundings, as well as the intensity and nature of the lighting source(s).
Diamonds of any color will do this.
Some fluorescent diamonds exhibit exaggerated changes based on lighting.
Nothing we say or do is going to change that.

Your logic seems busted to me.

GIA doesn't try to mimic and test every conceivable set of of real life viewing environments. Instead they utilize a DiamondDock to create a controlled lab viewing environment that allows them to produce repeatable and reliable results.

Learn What Diamond Color Is and What it Means | GIA 4Cs of Diamond Quality

Understand about diamond color and what the best color for adiamond is with GIA’s color scale classification.

4cs.gia.edu

Screen shot of GIA stone being color graded from video in the above web link:



By changing light bulbs, using a filter and/or changing distances you could change the UV intensity to zero (or near zero levels) so that you neutralize the effects of fluor when color grading -- all while doing nothing more than using the controlled lab environment already utilized to color grade diamonds.

Some fluorescent diamonds behave in a manner that makes them near impossible to color grade.

And this supports what I'm saying above. Since you can't remove the fluor from the stone to get stable test results, you have to remove the UV intensity level of the lighting to neutralize the effects.

Clearly you're free to tell your clients whatever you want.
IN a public discussion, questions will be raised. That is how education takes place.

I'm not sure if that statement was pointed at me, but I am not a WF client.

FWIW, I nearly bought one of their stones, but opted for a BGD stone instead. However, I would absolutely consider them as I feel they are a responsible vendor that provides a quality product.

 

[sledge]

4. I have raised several issues about Cowing's articles as in the past year or two I have learned a lot more information and identified flaws in that work. Mainly he did not really account for the changes in GIA's grading lighting, he used the wrong measuring Solarmeter, and did not properly account for violet and near violet effects which are common radiations all around us and have a much stronger effect than the previously considered much shorter wave length UV lights.

Happy to discuss any one of the above 4 points until we get some consensus.
Or any other individual fact or variant.

@Garry H (Cut Nut) would it be possible for you and some of the vendors such as WF, CBI and others to put together a new study concerning fluor?

For me I see two main issues:

1. The effects during color grading in a controlled lab.
2. The effects after grading in the real world.

It seems like addressing item #1 would be fairly simple and not too terribly expensive. Better yet, is this a study that vendors want to give involved in doing as I'm sure there could be some negative blow back as well.

At least it sounds simple. Use the correct meter you've mentioned. Take readings using various bulbs under various conditions (7" away, 10" away, 12" away, filters, etc).

 

[Garry H (Cut Nut)]

@Garry H (Cut Nut) would it be possible for you and some of the vendors such as WF, CBI and others to put together a new study concerning fluor?

For me I see two main issues:

1. The effects during color grading in a controlled lab.
2. The effects after grading in the real world.

It seems like addressing item #1 would be fairly simple and not too terribly expensive. Better yet, is this a study that vendors want to give involved in doing as I'm sure there could be some negative blow back as well.

At least it sounds simple. Use the correct meter you've mentioned. Take readings using various bulbs under various conditions (7" away, 10" away, 12" away, filters, etc).

Firstly Sledge, there are research programmes under way. More advanced than you can know.
Secondly, what ever we might come up with is not going to change GIA's methods, and all other labs follow them.
Thirdly, I think you should read the 2008 article I linked after I posted - so maybe you missed it. The lamp topic has been addressed https://www.gia.edu/doc/Coloring-Grading-D-to-Z-Diamonds-at-the-GIA-Laboratory.pdf

Regarding point 2. There are many people here on this forum who have enough diamonds and can all do the simple tests that I am doing. Nothing I am doing seems to have a hope in Hell of changing some peoples opinions.
One final point a CRI index of 90 is desirable for color grading. A point I have been making for a long time is low means that no matter what the diamond color is no one can tell.
If there is a high CRI then there will be plenty of 380nm to 415nm illumination creating heaps of blue N3 color enhancement in D-N diamonds (unless you are in a really bright LED environment like what MC used).

 

[OoohShiny]

@Garry H (Cut Nut) would it be possible for you and some of the vendors such as WF, CBI and others to put together a new study concerning fluor?

For me I see two main issues:

1. The effects during color grading in a controlled lab.
2. The effects after grading in the real world.

It seems like addressing item #1 would be fairly simple and not too terribly expensive. Better yet, is this a study that vendors want to give involved in doing as I'm sure there could be some negative blow back as well.

At least it sounds simple. Use the correct meter you've mentioned. Take readings using various bulbs under various conditions (7" away, 10" away, 12" away, filters, etc).

I like your idea but I fear accusations of 'vested interest' in making fluor more valuable! lol

 

[Texas Leaguer]

Garry,
The fact that alternate technologies exist or new technologies emerge does not necessarily invalidate older studies. You have mentioned numerous times that in your opinion the Cowing study used the wrong device to measure light content or intensities, and that it was focused on the wrong wavelength. Could you explain how that invalidates what the study reveals? Or the study's conclusions and recommendations?

Afterall, the study was done in response to an issue that many in the trade had already identified and were concerned about. The study itself involved a survey of diamonds with varying degrees of fluorescence and attempted to establish the problem, explain the root cause mechanisms, and make recommendations to solve or mitigate the problem.

The issue was considered of sufficient importance that many serious people in the trade (Martin Rapaport among them) attributed the unwarranted discounts (value loss) of fluorescent diamonds largely to the color grading problem.

365nm was used in the study because it was (and still is) the standard used in the labs for observing and reporting the fluorescent reaction. But it was also called out in the study that other wavelengths excite blue fluorescence, in particular wavelengths from 380-415 in the Visible Violet band of the spectrum. Thomas Hainscwhang’s 3D graph shows the different wavelengths and the strength of their effects. So the impact of VV is not ignored in this study, in fact it was highlighted.

But what difference does that make to the findings of the study? Grade whitening was observed in various lab grading environments and correlated to both the strength of fluorescence (observed at 365) and to the intensity/distance from the light source. 365 nm, VV and all wavelengths in between obey the same laws of physics and will similarly lose intensity and their fluorescence stimulating ability within a few inches of artificial light sources.

Much of your position on the visual impact of fluoro seems to center around environments with varying degrees of sunlight present. But the diamonds in the Cowing study were not graded in sunlight, nor were the stones in the GIA survey.

While doing a study on the visual impact of fluorescence on diamonds where varying intensities of sunlight are present is a worthwhile idea, that is not what Cowing et al studied. And it is not constructive to malign their work because they didn’t choose a different question to study and/or different measuring devices and wavelengths.

 

[Texas Leaguer]

A related factoid:
GIA has been doing color grading for some time now by machine. A subset of their stones are no longer graded by human graders. These are mostly small stones but there are other criteria that determine whether a stone is a candidate for machine grading on their proprietary device. Fluoresce is one of those criteria.