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Should we discourage or recommend FL stones?

Bryan and David,
I am concerned primarily with daylight indoors and out of doors as the source of excitation.
Please everyone try for yourself at night time with your best house hold lighting (not standing on a chair) to discern slight differences in diamonds of different color.
I can not see the difference between a D and an H even in my bathrooms with very bright tube lights (one with fluoro's and one with LEDs).
But in rooms with windows facing almost any direction it is much easier to SEE slight color differences.

So aside from fluoro whitening or not - we really need good natural light and that good light always has some of those wonderful low intensity, not damaging or sunburning, violetish rays will have some effect.
Still trying to work out how to measure the effect.
 
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Totally agree Garry. I’ve always color graded under a diamond lamp, in a room with windows, but never direct sunlight. When you remove the stone from under the lamp, natural light ( not direct sunlight) will allow color grading - as well as certain cool fluorescence effects (whitening). Although GIA does not use natural light, it’s very common for dealers to do so.
I could not grade color at night.
I’ve never tried in the bathroom though. I’d probably “pop” the stone and have to go fishing:)
 
Bryan, maybe you don't remember, or you weren't here ...but when my relationship with Garry started, we fought tooth and nail. I was sure of my positions and needed to open my mind to allow the benefit of expanding my knowledge- and the possibility of civil debate.
Not that Garry and I agree on everything, but I opened my mind to ASET, HCA, and other technological advances.
Today I consider myself extremely lucky to call Garry a friend.
I have nothing against you- I have no desire to argue.
Your refusal to acknowledge my real life, hands-on experience is truly frustrating.
I'm not lying, and neither are my eyes.
If you could just admit that there's debate about this- as opposed to settled science, we could actually discuss it.
Which I would welcome.
 
I wish Bryan would be willing to discuss.....
Clearly there’s debate among tradespeople. If this thread has achieved anything we can see that the science is developing- and there are no simple answers when we are considering fluorescence and diamonds.
 
The science of diamond fluorescence is extremely well understood. There is little, if any, debate about what causes diamonds to fluoresce - down to the specific atomic defects that give rise to different colors of fluorescence. Specialized fluorescence observations are a key tool in understanding diamond formation and separating natural and synthetic diamonds.

Anyone interested in understanding the science of diamond fluorescence can avail themselves to any number of scholarly articles referenced in this and other threads on the topic. This article was just brought to my attention and provides another example of the depth of our scientific understanding.

https://pdfs.semanticscholar.org/fd86/426ab45369629de85ab47ac287845b3a879c.pdf
(scroll down to second article)

The fact that some people are unaware of the science, do not fully understand it, or are unwilling to accept it - is another thing altogether.
 
I’m not a scientist- rather a lifelong diamond grader. I did read the article, as much as I could grasp. It was about the difficulty in color grading due to inconsistencies in lighting. Specifically diamond grading lamps.
The article mentioned all the specific lighting sources tested. I didn't see anything about "natural light" or "sunlight".....either indirect or direct. Maybe I missed something.
@Texas Leaguer , can you please show us where the article you linked to mentions sunlight, or natural light, or indirect sunlight?
I don’t know if you’re a scientist or not Bryan.
If you were, wouldn’t you want to study why these inconsistencies exist especially regarding direct and indirect sunlight? Especially if trusted experts in the field of diamond grading are reporting first-hand observations?
Lucky for us Garry is a scientist, and he's studying exactly that.
No one participating has produced established science regarding this particular aspect- which is vital to consumers.
Bryan is there a reason you're so heck bent on insisting that certain fluorescent diamonds can't be more desirable due to this aspect?
 
David,
I don't think anyone but you is questioning the science. There is a ton of information in the discussions already covered about the relative intensity of sunlight vs artificial lighting. If you are interested in learning, go back and re-read the materials that have already been introduced here and in the earlier threads.

It's redundant to be carrying on the same conversation with you, and what is more, we already agreed to disagree. And I spelled out for you my takeaways on diamond fluorescence based upon my personal observations over my career, and in light of the science. As previously mentioned, my views on the topic are not fundamentally in opposition to the studies and surveys that GIA has published, or the work Michael Cowing et al have published.

I don't see anyone else coming on to the thread with questions that I might be able to shed any light on, so my appetite for continuing to engage you on this topic is dropping off faster than UV intensity at distance from an overhead tube.
 
No problem Bryan- you can't show us even one sentence in the paper you just referenced that has anything to do with indirect sunlight's effect on fl diamonds.
Yet right here in this very thread, some answers to why we observe whitening indoors, not directly under a grading lamp, have been postulated. By other trade members, not by me.

Moving on- to consumers ( still ) reading....Certain I-J-K-L diamonds that possess Medium or strong blue fluorescence show color improvement ( whitening) when exposed to indirect sunlight- even through windows. There is nothing "scientific" to disprove this.
A key word is "certain". This is not a guarantee- not all MB/SB stones whiten. I've seen far more MB/SB stones that don't whiten.
Furthermore, if a consumer wants an H color- and they have the ability to discern slight differences in diamond color, buy an H.
My point is- don't be taken in by promises one way or the other. Observe the diamond for yourself in multiple viewing environments.
 
Texas Leaguer said:
Anyone interested in understanding the science of diamond fluorescence can avail themselves to any number of scholarly articles referenced in this and other threads on the topic. This article was just brought to my attention and provides another example of the depth of our scientific understanding.
https://pdfs.semanticscholar.org/fd86/426ab45369629de85ab47ac287845b3a879c.pdf
(scroll down to second article)
Click to expand...
Bryan, Bryan, Bryan!!!!
You only just read this article?
I have been quoting from it for years and several times in this thread!

And what about this one you are well aware of?
https://hrdantwerp.createsend1.com/...EF23F30FEDED/B873EB7D3FCA8FF40F8C96E86323F7F9
“HRD Antwerp, Europe’s leading authority in diamond certification, recently undertook a study entitled “The effect of fluorescence on the colour of a diamond”, concluding that even strong fluorescence does not negatively impact a diamond’s appearance. In fact, their findings demonstrate the contrary: under normal conditions and even when outdoors, strong fluorescence has a positive influence on the colour of diamonds. This finding directly contradicts the common perception that fluorescence is a negative property of diamonds, driving down their value. Given HRD Antwerp’s findings, they conclude there is no justification for the price penalties that currently apply to fluorescent diamonds.”

Surely you remember me stating that I found this example a bit over the top:
As an example, a diamond graded in the HRD Antwerp laboratory as a J colour with very strong fluorescence can appear as a D colour when examined in outdoor conditions.
I have seen strong G's that appear to be D, and we use Drena's 3ct F strong blue (which lives in the store safe, those who know her, know why) as an example to compare alongside non fluoro D's inside our store.
 
Garry H (Cut Nut) said:
Bryan, Bryan, Bryan!!!!
You only just read this article?
I have been quoting from it for years and several times in this thread!

And what about this one you are well aware of?
https://hrdantwerp.createsend1.com/...EF23F30FEDED/B873EB7D3FCA8FF40F8C96E86323F7F9
“HRD Antwerp, Europe’s leading authority in diamond certification, recently undertook a study entitled “The effect of fluorescence on the colour of a diamond”, concluding that even strong fluorescence does not negatively impact a diamond’s appearance. In fact, their findings demonstrate the contrary: under normal conditions and even when outdoors, strong fluorescence has a positive influence on the colour of diamonds. This finding directly contradicts the common perception that fluorescence is a negative property of diamonds, driving down their value. Given HRD Antwerp’s findings, they conclude there is no justification for the price penalties that currently apply to fluorescent diamonds.”

Surely you remember me stating that I found this example a bit over the top:
As an example, a diamond graded in the HRD Antwerp laboratory as a J colour with very strong fluorescence can appear as a D colour when examined in outdoor conditions.
I have seen strong G's that appear to be D, and we use Drena's 3ct F strong blue (which lives in the store safe, those who know her, know why) as an example to compare alongside non fluoro D's inside our store.
Click to expand...

The article I posted is a sister article (prequel?) to the one I was familiar with, which you also linked earlier in the thread. I only posted it as another example of how much is known to science about diamond fluorescence.

Do you have a link to the actual HRD study? I would like to see how it compares to the 1997 GIA study aimed at answering similar questions. The link you posted above is merely a summary of conclusions, which includes the following statement (my bold):

"It confirms that even very strong fluorescence has no detrimental effect on the appearance of diamonds in a laboratory setting, and when viewed through the pavilion in outdoor conditions, it results in a clear improvement in a diamond’s colour."
 
Texas Leaguer said:
The article I posted is a sister article (prequel?) to the one I was familiar with, which you also linked earlier in the thread.
It is the very same article Bryan.
The very same article that indicates that 365nm creates half the N3 blue fluoro as 405nm UV that is all around us and passes through windows.
It is why I would like Michael Cowing to admit he has been using the wrong device to measure UV.

Do you have a link to the actual HRD study?
I have not seen any other published article. Yoram DiaGem and I have posted that article here before.

I would like to see how it compares to the 1997 GIA study aimed at answering similar questions.
The main (unspoken) outcome of the 1997 GIa article was they realised that they had too much UV and diamonds were graded too close to the lamps. GIA changed but never realllly openly admitted that strong blue fluoro diamonds should get a lower color grade.

"It confirms that even very strong fluorescence has no detrimental effect on the appearance of diamonds in a laboratory setting, and when viewed through the pavilion in outdoor conditions, it results in a clear improvement in a diamond’s colour."
Click to expand...
I bolded a different section Bryan.
HRD is up for sale, so not sure they have advanced this research
 
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Garry H (Cut Nut) said:
I bolded a different section Bryan.
HRD is up for sale, so not sure they have advanced this research
Click to expand...

So I could own my own lab? Bwahaha.

Seriously, any details you can share on the sale?
 
sledge said:
So I could own my own lab? Bwahaha.

Seriously, any details you can share on the sale?
Click to expand...

Diamonds.net - HRD Antwerp Receives Two Takeover Bids

RAPAPORT... The International Gemological Institute (IGI) and industry veteran Peter Meeus have put in rival bids to acquire HRD Antwerp. Meeus, HRD’s former managing director, last week submitted a proposal to buy at least 51% of the lab in partnership with two unnamed individuals, he...
www.diamonds.net
 
I am thinking of how color is considered as an impression of the cut for fancy color diamonds, as opposed to grading body colour irrespective of cut. Any effect of fluorescence could be considered as it plays out against the effect of cut on color perception in the near-colourless range. This could clarify things - narrowing down details of perception one way or another.
 
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I think I understand what @AV_ is saying.
We grade fcd’s through the table as opposed to colorless being graded through the pavilion.
Am I on track av?
 
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Garry H (Cut Nut) said:
I bolded a different section Bryan.
HRD is up for sale, so not sure they have advanced this research
Click to expand...

Garry,
You are correct that it is same article. The different titles threw me. Regarding your quote below:

The article I posted is a sister article (prequel?) to the one I was familiar with, which you also linked earlier in the thread.
"It is the very same article Bryan.
The very same article that indicates that 365nm creates half the N3 blue fluoro as 405nm UV that is all around us and passes through windows.
It is why I would like Michael Cowing to admit he has been using the wrong device to measure UV".

How does the fact that the standard 365 nm was used to illustrate different intensities of fluoro stimulating wavelengths invalidate the key findings in the Cowing study? The study went to lengths to demonstrate relative intensities in various lighting environments and documented with observations how those intensities drop off dramatically at distances of inches from fluorescent tubes.

Setting aside for a minute the question of how much intensity of 405 might exist in sunlight coming in from a window at different distance (a different meter will be needed), if the 365 from artificial sources is too weak to stimulate color whitening levels of fluorescence, why would you assume the 405 wavelengths would not also be of proportionate weakness? Intensity of each wavelength would be dropping off at distance from the artificial source at the same rate.

The drop-off in intensities as explained mathematically can also be observed in the grading studies of Cowing et al. The GIA survey also indicates that average observers cannot see a whitening effect under typical viewing environments.

Your argument seems to be specific to lighting environments in which a portion of the light illuminating the diamond is sunlight coming through windows, and speculation that it contains enough intensity of 405 to produce whitening effects. But if 365 is heavily filtered by glass, especially with a coating, even if 405 produces a stimulating effect twice that of 365, having lost the 365 you are still back at a significant loss of stimulating wavelengths from sunlight coming through the window.
 
Bryan you are asking me to say the same things again and again.
so re read or we give up.
 
Garry,
I have made a sincere attempt to understand your postings over the years and several long threads, and to reconcile them with other credible information in the domain. I am really not trying to win an argument with you as much as I am trying to understand the source of our disagreement. So, if I am asking the same things again and again it is because I have not seen a clear answer.

In any case we should probably give up. We don't seem to be making much progress.

It's all good though. Maybe some people have learned some things by reading the articles and information to which we have linked that they otherwise would not have been exposed to.

Cheers!
 
Bryan- one of the hardest aspects of this thread- and others- is that you refuse to acknowledge my real-life experience.
Man to man, I'm asking- please get over this.
We're both here- we both share the same goal of education. Neither has anything against the other, either personally, or in a commercial sense.
I tell you I've witnessed whitening on countless occasions. In an attempt to prove I can't have seen what I've seen- or I simply made it up- you respond with an article. I'm sure you can understand how frustrating that is, from my perspective.

You have referred to- and we have contested certain aspects of it...but the Cowing article actually bolsters our point.
Please notice how Cowing uses the word "daylight" repeatedly in regards to whitening specifically. He does not use the word "sunlight". Daylight is what you have in the vast majority of rooms people spend time in, during the day, most days.
The debate about how much UV windows cut out is irrelevant to me, because I have seen this in so many locations. It's not about windows. Something contained in daylight, coming through windows, causes a color change in some stones.
Garry is working in that aspect, if that aspect is interesting to you.

I've made so many efforts to come to an amicable resolution.
I still feel that way.
Cheers to you my brother- and have a great Thanksgiving!!


Here are the quotes, from the beginning of the Cowing study
"Strong, and Very Strong blue fluorescence.Graduates of the GIA in the 1960’s through the early 90’s were taught that “Fluorescent diamonds should be graded at their color in artificial light devoid of ultraviolet radiation, rather than at their daylight appearance”. They learned that grading in daylight or fluorescent light with the attendant UV radiation will result in overgrading a blue fluorescing diamond. "

Further down
The problem is how to correctly grade blue-fluorescing diamonds, when they often appear a higher, whiter color grade in daylight than their color seen indoors under typical artificial lighting. The diamond’s color unimproved by fluorescence is observed at normal wearing and viewing distances from most all forms of artificial illumination including fluorescent lighting. We note from Wade that more than 30 years before the founding of the GIA, the trade valued a diamond based upon what the trade called its “true color”, as seen indoors in artificial light, not its fluorescence improved color.

In daylight, additional factors, including time of day, geographic location, and whether or not the day was sunny or cloudy cause the color of a fluorescent diamond to change. With the perceived color of fluorescent diamonds varying with the illumination, what lighting should be used in laboratory color grading?
 
Rockdiamond said:
Further down
The problem is how to correctly grade blue-fluorescing diamonds, when they often appear a higher, whiter color grade in daylight than their color seen indoors under typical artificial lighting. The diamond’s color unimproved by fluorescence is observed at normal wearing and viewing distances from most all forms of artificial illumination including fluorescent lighting. We note from Wade that more than 30 years before the founding of the GIA, the trade valued a diamond based upon what the trade called its “true color”, as seen indoors in artificial light, not its fluorescence improved color.
Click to expand...
 
Bryan, we all agree.
I'm even pointing out why there's an inconsistency.
If the sole form of illumination is artificial, you'd have to be extremely close to the bulb to activate fluorescence. This is the case after darkness.
In any room with a window, artificial light is not the sole source of illumination. The daylight overwhelms artificial lighting for much of the day.
That's why daylight is specifically mentioned.
 
Lets change tack a little Bryan.
Pre 2000 GIA overgraded color of diamonds. Agreed?
Micheal Cowing's article spends most of its effort based on +20 years ago.

consider the post 2000 GIa grading method (adopted by AGS and I believe IGI):
"The result was a change in the amount of UV excitation from upwards of 150µW/cm2 in the DiamondLite to the vicinity of 30 µW/cm2 at the grading tray in the DiamondDock; a five times reduction. The study found that this amount of UV reduction takes the typical amount of overgrading in Very Strong Blues from as much as four and a half grades down to two grades."

I will make a case that 4.5 divided by 5 = less than 1 grade "overgraded".
Micheal has exaggerated his case.

Can we agree on that?

The relevant quote is about 2/3rds of the way down:
https://www.pricescope.com/articles/blue-fluorescent-diamonds-color-grading-issues
 
Garry H (Cut Nut) said:
Lets change tack a little Bryan.
Pre 2000 GIA overgraded color of diamonds. Agreed?
Micheal Cowing's article spends most of its effort based on +20 years ago.

consider the post 2000 GIa grading method (adopted by AGS and I believe IGI):
"The result was a change in the amount of UV excitation from upwards of 150µW/cm2 in the DiamondLite to the vicinity of 30 µW/cm2 at the grading tray in the DiamondDock; a five times reduction. The study found that this amount of UV reduction takes the typical amount of overgrading in Very Strong Blues from as much as four and a half grades down to two grades."

I will make a case that 4.5 divided by 5 = less than 1 grade "overgraded".
Micheal has exaggerated his case.

Can we agree on that?

The relevant quote is about 2/3rds of the way down:
https://www.pricescope.com/articles/blue-fluorescent-diamonds-color-grading-issues
Click to expand...
I can agree that it's possible to cherry pick things in both the Cowing survey as well as the GIA survey. To me the takeaways from both studies are not really controverted by any scientific evidence. In fact, in some ways the two studies validate one another.

Cowing demonstrated how and why overgrading was taking place (and as you point out, some changes in lab color grading were made). GIA demonstrated that consumers could not distinguish any effects of fluourescence in normal viewing environments.

Both studies reveal that whitening takes indoors only when sufficient intensity of fluorescence stimulating wavelengths are present. In the case of artificial lighting whitening occurs only when diamonds are exposed within a few inches of the source.

You posit, as I understand it, that whitening takes place commonly in indoor environments because of VV coming through windows. Neither study focused on varying degrees of sunlight exposure, but we do know from the background science cited in both that UV intensity (and presumably VV) falls off dramatically from direct sunlight to diffuse sunlight (clouds) to indirect sunlight that may enter indoor environments through windows.

So, what is the intensity of the VV in a typical room with a window? And is it sufficient to stimulate grade whitening fluorescence? And how close to the window would you need to be for that to happen? And would the sunlight need to be direct? What if it was indirect or it was a cloudy day? I don't know because I have not seen any data on that specific issue. But I think it is highly doubtful in light of what we do know. And the GIA survey findings support that view.
 
Rockdiamond said:
Listen, I'll chip in if you make sure everything we submit is D/IF, or Fancy Vivid Yellow!
Click to expand...

Nooooooooooo

You think AGS and GIA are strict? You ain't seen nothing yet ;) :lol:
 
I would rather not pay $750. I hope it willl be in the hard coy of the magazine when it comes:
The November Rapaport Research Report examines why diamonds with fluorescence sell at a significant discount to those without it.

RAPAPORT... The diamond industry has a complicated relationship with fluorescence.

Historically, both the trade and consumers saw value in a diamond that fluoresced under ultraviolet light. The perception was that it added to the color of the diamond while also providing various niche marketing opportunities. Take the ’80s disco era, when neon was in and a glow-in-the-dark diamond might have been cool.

But the positive view of fluorescence has changed over time — at least, from the trade’s perspective. Various periods of oversupply, and one or two scandals related to the subject, led the trade to discount diamonds with varying degrees of fluorescence. We explore this issue in the November issue of Rapaport Research Report and present our updated guidelines to what those discounts are. The higher the color, the more fluorescence negatively affects price.

The discounts are puzzling. The Gemological Institute of America (GIA) published a comprehensive paper on fluorescence in 1997, in which it challenged the notion that this trait had a negative impact on higher color diamonds. If anything, the GIA concluded, fluorescence adds to lower colors, and it does not affect a diamond’s transparency.

Most importantly, the GIA found that the jewelry-buying public saw no difference between diamonds with fluorescence and those without. It wasn’t an issue for the consumer back then, and it isn’t today, according to most of the diamond professionals we consulted for the report.

If that is true, the trade is missing out on an opportunity. The biggest challenge facing the industry is figuring out how to broaden demand, which has narrowed over the past decade as buyers have become more specific in their requirements. As a result, there is an oversupply of diamonds that are difficult to sell. In many cases, it’s because they are fluorescent goods.

We’re seeing a recovery in demand for stones with faint or no fluorescence, and continued weakness among diamonds in the medium, strong and very strong categories. That’s difficult to understand if the consumer isn’t too bothered about the issue.

And therein lies the opportunity: Savvy diamantaires and jewelers are buying fluorescent goods and marketing them as a specialized product. Some big sellers — most notably Alrosa — have a lot of fluorescence in their production and are trying to create a category for those stones. Considering that the industry needs an avenue for offloading its fluorescent diamonds, it should be encouraging initiatives like these.

To download the full report as a subscriber to the Rapaport Research Report, or to subscribe, click here.
 
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