Fluorescence (revisited)

[tinatark]

I never considered a stone with fluorescence - until my dh lost my ring a little over 2 years ago - I went into one of the stores my homeowner's insurance "recommended" - one of the higher end stores in my area. The rep said he had a stone I just had to see - it was a K with strong blue fluorescence. We looked at it and knew almost immediately it was the one! It has the steely white look, like the DF's.

I paid quite a bit less for it than I would have for one with no Fl. 2.09 GIA XXX SI2, K.

I love the fluorescence! Have my own black light - we've checked out ALL our jewelry It's awesome when I'm in the tanning bed!

 

[Texas Leaguer]

David et al,
In regards to the request for snippets from the 2010 study that are relevant to this particular discussion, I have assembled a few below in quotes. An essential point of this thread is whether common beliefs about visual appearance of diamonds with fluorescence are supported by current scientific understanding. The fluorescent effect is a result of temporary excitement of certain impurities within the diamond by ultraviolet radiation (and some visible violet). If that excitement does not take place, no visual effects from the fluorescence can be observed. The presence of a UV component alone is not sufficient to activate the effect. The UV must be of a sufficient intensity for activation to take place. The studies on artificial lighting show that distance from the source has a significant bearing on intensity levels.

The study concluded that “At normal viewing distances from artificial illumination the violet light intensity, just like the UV, is too weak to excite noticeable fluorescence.”

Even daylight is highly variable in terms of both the amount and range of wavelengths present and intensity levels, depending on things like time of year, time of day, and cloud cover. And daylight coming through windows is further UV filtered to different degrees by the glass.

For some of the more technical statements and measurements, this passage which accompanies various technical graphs is relevant:

“Away from open daylight and indoors, the UV intensities dropped by factors of 100 to 1000, and in typical artificial light to less than 1µW/cm2 . The greatest indoor sources of UV at noon were large glass windows and doors which faced daylight. These large glass areas filter out short wave UV, but pass a proportion of long wave UV. At the window surface the reading at the December 2008 date and time was 150 µW/cm2 dropping to 65 µW/ cm2 at 3 ft and 35 µW/cm2 at 6 ft. In all other areas illuminated by artificial fluorescent and incandescent ceiling illumination the readings at typical 3–4 ft viewing distances from ceiling lights were an essentially UV-free, 0–1 µW/cm2 . These readings are consistent with results from extensive surveys conducted by the author and others and provide support for the observation that at distances of more than 3 ft from artificial illumination, including ceiling mounted fluorescent lighting, indoor light is essentially UV free.”

To put those numbers into perspective there is this statement regarding readings taken outdoors : “Near but not including direct sun, the reading quickly exceeded the meter range of 1999 µW/cm². Hazy overcast and cloudy skies absorb UV and were observed to reduce these figures by more than a factor of two. On 8 March 2009 at noon on an overcast day readings in north light of 800–1100 µW/cm² were obtained.

In looking at color grading at the labs and in the trade, differences in equipment and procedures resulted in different viewing distances from the light source (which is now unfiltered for UV) - anywhere from 2-3 inches to around 10 inches. As an example of how dramatically UV intensity drops off with just a small amount of distance, there is this statement regarding grading in the Diamond Dock: “The UV intensity is 65% higher at 7 in. compared to that at 10 in.”

Here are a few of the recent threads about fluorescence where these and other related issues have been discussed.

[URL='https://www.pricescope.com/community/threads/wish-i-would-have-discovered-ps-sooner.210551/']https://www.pricescope.com/community/threads/wish-i-would-have-discovered-ps-sooner.210551/[/URL]

[URL='https://www.pricescope.com/community/threads/fluorescence-pros-and-cons.211191/']https://www.pricescope.com/community/threads/fluorescence-pros-and-cons.211191/[/URL]

[URL='https://www.pricescope.com/forum/journal-article-discussion-new/help-evaluating-a-diamond-t210087.html']https://www.pricescope.com/forum/journal-article-discussion-new/help-evaluating-a-diamond-t210087.html[/URL]

Amazing stuff Bryan- thank you for compiling it.
Some of the measurements are telling unto themselves- and correlate what I see in real life.
Basically there's a lot of variables.

“Away from open daylight and indoors, the UV intensities dropped by factors of 100 to 1000, and in typical artificial light to less than 1µW/cm2 .

Factors of 100-1000 imply a large variation possible.
"Typical artificial Light" is also quite overly general. Not trying to disagree with the findings- I think they leave room for interpretation.
I agree that in dim lighting, any color change effect is next to impossible to see. But a lot of people report noticing the blue in places like Costco. Many rooms also have sunlight as one of the lighting sources during the daytime.

You mentioned that impurities within the diamond are the root cause of fluorescence. Based on that, we can also deduce that "impurities" by their very nature, will vary from one to the next.
Again, jibes with real life:
We all know that a small percentage of MB, and SB ( or other colors besides blue) are hazy- sleepy- milky. Dull and undesirable.
Maybe the particular impurities in those diamonds are of a different nature than the majority of stones- the ones which don't show haziness.
Taking this a step further, within this majority of stones, this group which is not hazy under normal light- or even direct sunlight- there's distinct variations in this group as well.
I've seen many cases of stones that looked very similar in the dark, under UV, yet performed differently, in terms of the chameleon- like aspect of the fluorescence in daylight.
Conversely, many cases of stones that performed very differently in the dark under a UV, yet looked just about identical in daylight.
maybe it's these variations in light- combined with the structure of the diamond, and how it reacts to the impurities within that cause what I- and many other dealers- and consumers have noticed.

I understand why consumers might shy away- Fluorescence is a "question mark" - why risk it?

Especially with an internet purchase. That makes sense.
But if one is willing to look, there's reasons to consider FL diamonds. Always get a money back guarantee, and dealing with a vendor that can eyeball the diamond are good rules of thumb.
If you look at a lot of stones, some fluorescent ones have something very special. That's one reason why I won't reject a stone based solely on florescence.
The other reason is price.
Particularly in higher color stones, the discount for MB or SB can be 25%.
In a high color 2ct stone that can add up to some serious buck.

I completely agree that there is no reason not to buy a stone with fluorescence if you understand the property and the diamond has the attributes you desire. To a large extent fluoro is simply an identifying characteristic that helps us differentiate stones with similar 4 C's. And I think most of us agree that it is a cool, trippy, magical property that adds interest to the diamond.

For me the key takeaways from the research are; The commonly touted benefits to color appearance are essentially invalid from a real world perspective (likewise the problem with haziness due solely to fluoro is overblown). The problem of overgrading for color is documented yet the labs are still using problematic practices. And the market punishes the property, which can be good if you are buying (provided the stone is not overgraded for color in the first place), but is very bad when a consumer goes to sell.

 

[Rockdiamond]

David et al,
In regards to the request for snippets from the 2010 study that are relevant to this particular discussion, I have assembled a few below in quotes. An essential point of this thread is whether common beliefs about visual appearance of diamonds with fluorescence are supported by current scientific understanding. The fluorescent effect is a result of temporary excitement of certain impurities within the diamond by ultraviolet radiation (and some visible violet). If that excitement does not take place, no visual effects from the fluorescence can be observed. The presence of a UV component alone is not sufficient to activate the effect. The UV must be of a sufficient intensity for activation to take place. The studies on artificial lighting show that distance from the source has a significant bearing on intensity levels.

The study concluded that “At normal viewing distances from artificial illumination the violet light intensity, just like the UV, is too weak to excite noticeable fluorescence.”

Even daylight is highly variable in terms of both the amount and range of wavelengths present and intensity levels, depending on things like time of year, time of day, and cloud cover. And daylight coming through windows is further UV filtered to different degrees by the glass.

For some of the more technical statements and measurements, this passage which accompanies various technical graphs is relevant:

“Away from open daylight and indoors, the UV intensities dropped by factors of 100 to 1000, and in typical artificial light to less than 1µW/cm2 . The greatest indoor sources of UV at noon were large glass windows and doors which faced daylight. These large glass areas filter out short wave UV, but pass a proportion of long wave UV. At the window surface the reading at the December 2008 date and time was 150 µW/cm2 dropping to 65 µW/ cm2 at 3 ft and 35 µW/cm2 at 6 ft. In all other areas illuminated by artificial fluorescent and incandescent ceiling illumination the readings at typical 3–4 ft viewing distances from ceiling lights were an essentially UV-free, 0–1 µW/cm2 . These readings are consistent with results from extensive surveys conducted by the author and others and provide support for the observation that at distances of more than 3 ft from artificial illumination, including ceiling mounted fluorescent lighting, indoor light is essentially UV free.”

To put those numbers into perspective there is this statement regarding readings taken outdoors : “Near but not including direct sun, the reading quickly exceeded the meter range of 1999 µW/cm². Hazy overcast and cloudy skies absorb UV and were observed to reduce these figures by more than a factor of two. On 8 March 2009 at noon on an overcast day readings in north light of 800–1100 µW/cm² were obtained.

In looking at color grading at the labs and in the trade, differences in equipment and procedures resulted in different viewing distances from the light source (which is now unfiltered for UV) - anywhere from 2-3 inches to around 10 inches. As an example of how dramatically UV intensity drops off with just a small amount of distance, there is this statement regarding grading in the Diamond Dock: “The UV intensity is 65% higher at 7 in. compared to that at 10 in.”

Here are a few of the recent threads about fluorescence where these and other related issues have been discussed.

[URL='https://www.pricescope.com/community/threads/wish-i-would-have-discovered-ps-sooner.210551/']https://www.pricescope.com/community/threads/wish-i-would-have-discovered-ps-sooner.210551/[/URL]

[URL='https://www.pricescope.com/community/threads/fluorescence-pros-and-cons.211191/']https://www.pricescope.com/community/threads/fluorescence-pros-and-cons.211191/[/URL]

[URL='https://www.pricescope.com/forum/journal-article-discussion-new/help-evaluating-a-diamond-t210087.html']https://www.pricescope.com/forum/journal-article-discussion-new/help-evaluating-a-diamond-t210087.html[/URL]

Amazing stuff Bryan- thank you for compiling it.
Some of the measurements are telling unto themselves- and correlate what I see in real life.
Basically there's a lot of variables.

“Away from open daylight and indoors, the UV intensities dropped by factors of 100 to 1000, and in typical artificial light to less than 1µW/cm2 .

Factors of 100-1000 imply a large variation possible.
"Typical artificial Light" is also quite overly general. Not trying to disagree with the findings- I think they leave room for interpretation.
I agree that in dim lighting, any color change effect is next to impossible to see. But a lot of people report noticing the blue in places like Costco. Many rooms also have sunlight as one of the lighting sources during the daytime.

You mentioned that impurities within the diamond are the root cause of fluorescence. Based on that, we can also deduce that "impurities" by their very nature, will vary from one to the next.
Again, jibes with real life:
We all know that a small percentage of MB, and SB ( or other colors besides blue) are hazy- sleepy- milky. Dull and undesirable.
Maybe the particular impurities in those diamonds are of a different nature than the majority of stones- the ones which don't show haziness.
Taking this a step further, within this majority of stones, this group which is not hazy under normal light- or even direct sunlight- there's distinct variations in this group as well.
I've seen many cases of stones that looked very similar in the dark, under UV, yet performed differently, in terms of the chameleon- like aspect of the fluorescence in daylight.
Conversely, many cases of stones that performed very differently in the dark under a UV, yet looked just about identical in daylight.
maybe it's these variations in light- combined with the structure of the diamond, and how it reacts to the impurities within that cause what I- and many other dealers- and consumers have noticed.

I understand why consumers might shy away- Fluorescence is a "question mark" - why risk it?

Especially with an internet purchase. That makes sense.
But if one is willing to look, there's reasons to consider FL diamonds. Always get a money back guarantee, and dealing with a vendor that can eyeball the diamond are good rules of thumb.
If you look at a lot of stones, some fluorescent ones have something very special. That's one reason why I won't reject a stone based solely on florescence.
The other reason is price.
Particularly in higher color stones, the discount for MB or SB can be 25%.
In a high color 2ct stone that can add up to some serious buck.

I completely agree that there is no reason not to buy a stone with fluorescence if you understand the property and the diamond has the attributes you desire. To a large extent fluoro is simply an identifying characteristic that helps us differentiate stones with similar 4 C's. And I think most of us agree that it is a cool, trippy, magical property that adds interest to the diamond.

For me the key takeaways from the research are; The commonly touted benefits to color appearance are essentially invalid from a real world perspective (likewise the problem with haziness due solely to fluoro is overblown). The problem of overgrading for color is documented yet the labs are still using problematic practices. And the market punishes the property, which can be good if you are buying (provided the stone is not overgraded for color in the first place), but is very bad when a consumer goes to sell.

We're pretty much in agreement- aside for the sentence in blue.
The research paper in question makes assumptions that are contrary to GIA literature, as well as real world observations of me- and countless others who do see a bump in color on MB or SB I-J-K colored diamonds in real world observation.

 

[kenny]

I completely agree that there is no reason not to buy a stone with fluorescence if you understand the property and the diamond has the attributes you desire.

I disagree.
A diamond with high fluor may take longer for a private party to sell because of widespread ignorance about fluor.

You can argue that what I'm saying contributes to fluro's unfair stigma.
That's true.
But you can go ahead and buy a diamond with high fluor to support the worthy cause, but don't complain and just take your lumps if you ever want to sell it.
Which way you go is your personal choice ... but IMO you should be fully informed about the reality of the effect of fluor on the second-hand diamond market.

But the fact remains, fluor sells at a discount because of the widespread (and IMO unfair) impression that fluor is undesirable.

 

[Rockdiamond]

Kenny- if a 1ct D/VS1 NONE sells for $7k, and a 1ct D/VS SB sells for $5500 ( hypothetical numbers that reflect real world prices) wouldn't there be a possibility that the buyer spending $5500 will loose less in the event of a resale- there's no doubt they have less to recover. The less costly stone is likely easier to sell.
If a J/VS1 None sells for the same price as a J/VS1 SB, but the SB stone just looks whiter, that might make it easier to recover the investment in the case of resale.

Of course this is all not very relevant to educated diamond consumers who are aware that as a purely financial investment, diamonds are not the best choice anyway.

 

[Texas Leaguer]

I completely agree that there is no reason not to buy a stone with fluorescence if you understand the property and the diamond has the attributes you desire.

I disagree.
A diamond with high fluor may take longer for a private party to, some day, sell because of widespread ignorance about fluor.

You can argue that what I'm saying contributes to fluro's unfair stigma.
That's true.
But you can go ahead and buy a diamond with high fluor to support the worthy cause, but don't complain and just take your lumps if you ever try to sell it.
That's a personal choice.

But the fact remains, fluor sells at a discount because of the widespread (and IMO unfair) impression that fluor is undesirable.

Actually, I think we completely agree Kenny. When I say there is no reason not to buy a fluro stone "if you understand the property" I mean that in the comprehensive sense of the word. Market realities and liquidity are a big part of what needs to be understood about fluro stones before you can decide if it is right for you.

The stigma may be unfair but it is a reality nonetheless. It may have developed partly through ignorance, but certainly a component of the discounting of fluoro stones stems from the overgrading issue. The trade has known about this for a long time (certainly before the 2010 study demonstrated it so dramatically) and has been a factor in offer prices for a long time. In other words, they tend to offer a price equivalent to a color grade or two lower than the report states to protect themselves in case the stone got a favorable color grade as a result of the fluoro.

The intent of the Cowing study, as articulated by the author, was to bring about a change in grading practices such that accuracy could be restored and the stigma against fluro could be eliminated.

 

[kenny]

Thanks Bryan.

 

[decisively_unsure]

There is something about a D-F diamond with no to nil fluorescence especially in sunlight.

 

[decisively_unsure]

"No to faint" even!

 

[lknvrb4]

There is something about a D-F diamond with no to nil fluorescence especially in sunlight.

I have had an F pear and and now have a J with fluorescence and hands down the J wins.

 

[decisively_unsure]

With that sort of comparison then fluorescence isn't really something to worry about.

It can help and balance a lot of stones, with different cuts there are far more important things, but you don't want it if you are in the high colours for my own tastes.

 

[Diamond_Hawk]

Bryan, Kenny, David and others:

Great exchange on this topic. I was kind of sad to see consensus start to build!

Though the studies can be shared, analyzed and debated, there is a consistent and undeniable stigma attached to the fluorescence in diamonds. But it is also a selling point because of the price differential. A customer with an obvious preference for size can be directed toward a SB diamond which will allow a size increase on a similar budget. If the stigma of fluorescence diminishes and the inevitable price equalization occurs, can't it be argued it gives the consumer fewer options?

 

[Texas Leaguer]

Bryan, Kenny, David and others:

Great exchange on this topic. I was kind of sad to see consensus start to build!

Though the studies can be shared, analyzed and debated, there is a consistent and undeniable stigma attached to the fluorescence in diamonds. But it is also a selling point because of the price differential. A customer with an obvious preference for size can be directed toward a SB diamond which will allow a size increase on a similar budget. If the stigma of fluorescence diminishes and the inevitable price equalization occurs, can't it be argued it gives the consumer fewer options?

Hawk,
Donde frijole cabrito?

Personally, I don't think stigmas are helpful to the consumer in any way. What consumers need is accurate, balanced information. They are not getting that in today's market with all of the marketing spin and misinformation swirling about the topic. I think if the labs did their part, the stigma would be reduced and prices would become rational. Of course the labs can't do it themselves, the trade also must become more knowledgeable about the subject and ethical in their representations.

 

[Rockdiamond]

Bryan, Kenny, David and others:

Great exchange on this topic. I was kind of sad to see consensus start to build!

Though the studies can be shared, analyzed and debated, there is a consistent and undeniable stigma attached to the fluorescence in diamonds. But it is also a selling point because of the price differential. A customer with an obvious preference for size can be directed toward a SB diamond which will allow a size increase on a similar budget. If the stigma of fluorescence diminishes and the inevitable price equalization occurs, can't it be argued it gives the consumer fewer options?

Thank you Brian!
I'm in favor of the current system- because it's easy to take advantage of the misconceptions to get a bargain.

I think the only area where Bryan and I disagree is the physical advantages I see in some fluorescent diamonds which Bryan feels does not exist- I don't think we're going to reach consensus on that, so we're still looking at a debate

 

[Texas Leaguer]

Bryan, Kenny, David and others:

Great exchange on this topic. I was kind of sad to see consensus start to build!

Though the studies can be shared, analyzed and debated, there is a consistent and undeniable stigma attached to the fluorescence in diamonds. But it is also a selling point because of the price differential. A customer with an obvious preference for size can be directed toward a SB diamond which will allow a size increase on a similar budget. If the stigma of fluorescence diminishes and the inevitable price equalization occurs, can't it be argued it gives the consumer fewer options?

Thank you Brian!
I'm in favor of the current system- because it's easy to take advantage of the misconceptions to get a bargain.

I think the only area where Bryan and I disagree is the physical advantages I see in some fluorescent diamonds which Bryan feels does not exist- I don't think we're going to reach consensus on that, so we're still looking at a debate

David,
The debate you are talking about only exists because you want it to. I have not heard anyone disputing the scientific findings relating to the fact that fluorescence is not activated in normal lighting environments. If the science is true there really are no "physical advantages" as you (and many others) like to suggest.

So if you want to continue a debate with folklore as the basis of your argument, you can certainly do so. But consumers are better served by understanding the facts.

 

[Rockdiamond]

There is something about a D-F diamond with no to nil fluorescence especially in sunlight.

I have had an F pear and and now have a J with fluorescence and hands down the J wins.

Am I making this up Bryan?
Consumers are best served with accurate info,
You're citing a single non conclusive study- which is controverted by GIA- as well as countless consumers' experiences, many experienced people within the trade- and little old me...I'm by no means the only one who see color changing effects of fluorescence in many lighting scenarios.
Therefore, if a consumer is told by an honest seller- "Yes, this J looks whiter than a non fluorescent J"- the statement is not inherently dishonest.
This is in stark contrast to a seller claiming: "EGL is just as good as GIA- you'll save money buying an EGL certified stone"

 

[Texas Leaguer]

There is something about a D-F diamond with no to nil fluorescence especially in sunlight.

I have had an F pear and and now have a J with fluorescence and hands down the J wins.

Am I making this up Bryan?
Consumers are best served with accurate info,
You're citing a single non conclusive study- which is controverted by GIA- as well as countless consumers' experiences, many experienced people within the trade- and little old me...I'm by no means the only one who see color changing effects of fluorescence in many lighting scenarios.
Therefore, if a consumer is told by an honest seller- "Yes, this J looks whiter than a non fluorescent J"- the statement is not inherently dishonest.
This is in stark contrast to a seller claiming: "EGL is just as good as GIA- you'll save money buying an EGL certified stone"

If comparing two stones in normal viewing environments - one with and one without fluoro- the fluoro stone can certainly look better, brighter, whiter, and more beautiful. But for reasons completely unrelated to fluorescence.

I do not believe that everyone who thinks that fluorescence in normal viewing environments improves a diamonds appearance is being dishonest. We are all influenced by what we have always heard. And often we truly believe things that turn out not to be the case later on. (Didn't the sun and stars all revolve around the earth at one time?) It is easy enough to see how one could look at a beautifully made fluoro stone and compare it to a similar stone with no fluoro and not cut as well or with different clarity features, and strongly prefer the fluoro stone. In that case it is easy enough to understand how that person comes away with a strong conviction that fluoro is a true benefit. Especially in light of many other people making similar claims.

You mention the GIA survey. It is very interesting and quite ironic that indications of the overgrading issue are actually right there in the GIA photos of their survey stones. Just look at the lineup of "I" colors and you can see some stones that look obviously darker in the photograph. The dark stones happen to correspond to the stones with strong fluoro. But they were all graded "I" color. What that means is that the fluoro fooled the graders and when you get those stones away from intense UV (into normal lighting environments) , instead of having improved color, the color appearance drops to the true body color!

 

[pfunk]

Bryan,

In your experience have you ever examined a fluorescent stone that improved in color appearance (ie became whiter) when viewing it in lighting high in UV such as sunlight?

Likewise, have you ever examined a fluorescent stone that improved in color appearance when indoors with light passing through windows?

Is it your opinion that diamonds with fluorescence only become whiter in strong UV which can only be achieved in full sunlight?

The whole debate reminds me of ones we have had on superideal and cut perfection. There aren't lab metrics showing that a superideal is performing any better than any other AGS 000, yet yourself and others certainly see a difference. Isn't it plausible, therefore, that people are seeing a noticeable improvement from fluoro that you personally aren't?

 

[Texas Leaguer]

Bryan,

In your experience have you ever examined a fluorescent stone that improved in color appearance (ie became whiter) when viewing it in lighting high in UV such as sunlight?

Likewise, have you ever examined a fluorescent stone that improved in color appearance when indoors with light passing through windows?

Is it your opinion that diamonds with fluorescence only become whiter in strong UV which can only be achieved in full sunlight?

The whole debate reminds me of ones we have had on superideal and cut perfection. There aren't lab metrics showing that a superideal is performing any better than any other AGS 000, yet yourself and others certainly see a difference. Isn't it plausible, therefore, that people are seeing a noticeable improvement from fluoro that you personally aren't?

P,
I'm glad you have joined this discussion and I hope you have read the GIA and Cowing studies that have been referenced. If not, I hope you will do so. You have a great ability to break things down, and you are not one to just accept the status quo!

In a way it is the opposite of the superideal question in terms of people's perception. In that case there are ways that we can demonstrate a greater degree of cutting precision and the question is, can it be appreciated visually?
Here we have a situation where the science says that an effect is not active under normal viewing environments yet people claim to see beneficial effects anyway.

In answer to your questions about my observations, yes I have seen fluorescent stones that inprove in aparent color in direct sunlight. This is very much in keeping with the science.With regard to observing the effect with sunlight passing through windows I would say that I have also observed the effect in that scenario, but in those cases is was probably highly intentional and observation was made very close to the window. This too is consistent with the science.

It is my opinion now, in view of my own experience as well as the science I have read and experts I have talked to, that fluoro diamonds can appear whiter either by exposure to direct sunlight outdoors (and possibly very close to a window) or by observation under artificial light containing UV wavelengths when the diamond is positioned within inches of the light source. In virtually every other lighting scenario I believe there is no visible effect.

 

[pfunk]

Bryan,

I must admit I have not yet read through the studies, but certainly intend to before I do any more commenting here. I was just joining the party late and was curious what your personal, real world experiences were with fluorsecence. I have read your posts in the past and have been able to glean that you oppose current grading procedures as they can give stones with fluorescence an unfairly high color grade. What I wasn't sure of was whether you personally felt that the effects of fluoro could be seen in typical lighting environments.

I imagine the links to both studies can be found somewhere in this thread and I look forward to reading through both of them and contributing further here. In the mean time, as Diamond Hawk said, good exchanges in this thread that have made it an enjoyable read!

 

[Rockdiamond]

Bryan- I respect scientific observations.
I am not "anti science"
But using the name of science loosely is a problem.

Here we have a situation where the science says that an effect is not active under normal viewing environments yet people claim to see beneficial effects anyway.

You are citing ONE study- which is disputed by other well respected organizations- ( GIA)

Therefore, it's really a stretch to claim "science says" we can't see what we are clearly seeing.

In fact, the premise of the study you cite is that diamonds are over-graded precisely due to the phenomenon I and many others have observed. That was the focus of the paper IMO- aspects regarding how visible the effect which causes the over-grading is under room lighting was not the prime aspect of the paper.

Just today I was looking at pear shaped diamonds for purchase.
I pulled one out and immediately noticed that there was blue.
This was in normal room lighting- not directly under a grading light, nor in direct sunlight.
Guess what GIA said?
Strong blue fluorescence.

I agree that color grading is affected by fluorescence.
But you don't need a special light to notice the effect.

 

[Garry H (Cut Nut)]

I am late to the party and confess i have only skimmed the posts here - so rap me if I make a dumb statement please.

1. I have spoken to Michael Cowing about his article. And Marty Haske too. GIA have changed their grading lamps and I do not believe they over grade strong blue fluoro diamonds. My argument with Michael is that when ever there is enough light in a room to be able to clearly see any colour in a diamond (say below F) that there will be enough UV to make GIA's grading accurate. e.g. an I STR Blue that GIA grades as H will appear to be H in any light that is good enough to see the H colour. I may need to qualify that in the new world where all artificial lighting is from LED's - but for now that is a practical case IMO.

2. High colour D-E-F diamonds blue fluoro appear to be more beautiful than non fluoro diamonds to most people who we might consider to be experts - that includes consumers who know in many cases way more than industry drones.

3. There was a fluoro article published by GIA about 2-3 years ago that looked at a wider range of UV frequencies than the 2 we use as gemologists based on the only easily available UV fluoro tubes. Personally I perfer to use the inexpensive near daylight UV LED little lamps because I think the response is closer to what we most often see in our every day environments. (These lamps also help remove any bad effects caused by very strong high energy shorter wave length UV lights that can temporarily fade coloured diamonds - e.g. Argyle pink diamonds.)

 

[Rockdiamond]

I am late to the party and confess i have only skimmed the posts here - so rap me if I make a dumb statement please.

1. I have spoken to Michael Cowing about his article. And Marty Haske too. GIA have changed their grading lamps and I do not believe they over grade strong blue fluoro diamonds. My argument with Michael is that when ever there is enough light in a room to be able to clearly see any colour in a diamond (say below F) that there will be enough UV to make GIA's grading accurate. e.g. an I STR Blue that GIA grades as H will appear to be H in any light that is good enough to see the H colour. I may need to qualify that in the new world where all artificial lighting is from LED's - but for now that is a practical case IMO.

2. High colour D-E-F diamonds blue fluoro appear to be more beautiful than non fluoro diamonds to most people who we might consider to be experts - that includes consumers who know in many cases way more than industry drones.

3. There was a fluoro article published by GIA about 2-3 years ago that looked at a wider range of UV frequencies than the 2 we use as gemologists based on the only easily available UV fluoro tubes. Personally I perfer to use the inexpensive near daylight UV LED little lamps because I think the response is closer to what we most often see in our every day environments. (These lamps also help remove any bad effects caused by very strong high energy shorter wave length UV lights that can temporarily fade coloured diamonds - e.g. Argyle pink diamonds.)

Hi Garry, you may be late, but surely welcome!!

The part in bold is probably the source of my disagreement with Bryan.
If you can see the color in a diamond, the strong likelihood is that there's sufficient quantity and quality of light to "activate" the fluorescence. Personally I don't know that the new crop of UV lighting will change this- but we have some at home, I will test it.

By the way, the opposite state of affairs exists with Natural Yellow Diamonds. This might even be relevant-
If a stone has medium or strong blue, GIA downgrades it's intensity.
The net effect is that in normal lighting environments a Fancy Yellow SB may look as dark as a Fancy Intense Yellow inert.

 

[Garry H (Cut Nut)]

By the way, the opposite state of affairs exists with Natural Yellow Diamonds. This might even be relevant-
If a stone has medium or strong blue, GIA downgrades it's intensity.
The net effect is that in normal lighting environments a Fancy Yellow SB may look as dark as a Fancy Intense Yellow inert.

Agreed David, and it is worth noting that GIA use totally different light boxes like the Judge to grade fancy coloured diamonds. And in my experiance they have a lot stronger illumination - but not sure how much UV is exposed from the lamps - which are however further away - so it may not be that GIA are downgrading because of UV - it may be they are grading what they see in those light boxes!

 

[Texas Leaguer]

Hi Garry,
Appreciate your participation here. Interesting points about the different devices/procedures used to grade fancy colors. I was not aware of that. It does point up the variables introduced by different light sources, devices and procedures being imployed by the labs and in the trade in assessing fluorescence. And the changes that take place that might affect consistency of grading over time.

I was also not aware that GIA has changed their color grading lamps or procedures since the Cowing study. Can you elaborate on that? Was it a response to the study?

 

[Garry H (Cut Nut)]

Hi Garry,
Appreciate your participation here. Interesting points about the different devices/procedures used to grade fancy colors. I was not aware of that. It does point up the variables introduced by different light sources, devices and procedures being imployed by the labs and in the trade in assessing fluorescence. And the changes that take place that might affect consistency of grading over time.

I was also not aware that GIA has changed their color grading lamps or procedures since the Cowing study. Can you elaborate on that? Was it a response to the study?

I believe the diamond story that Michael showcased in his article that dropped 4 grades when UV light was screened out of a grading lamp was graded a long time ago. GIA never formally 'announced' they changed their grading lamps - but Marty Haske drove them nuts and I suspect it was about 15 years ago. Michaels influence would have been way less than Marty's - you can search on this forum some references from Martin. His website has disappeared - I think he is unwell. Anyone know?

 

[Texas Leaguer]

Hi Garry,
Appreciate your participation here. Interesting points about the different devices/procedures used to grade fancy colors. I was not aware of that. It does point up the variables introduced by different light sources, devices and procedures being imployed by the labs and in the trade in assessing fluorescence. And the changes that take place that might affect consistency of grading over time.

I was also not aware that GIA has changed their color grading lamps or procedures since the Cowing study. Can you elaborate on that? Was it a response to the study?

I believe the diamond story that Michael showcased in his article that dropped 4 grades when UV light was screened out of a grading lamp was graded a long time ago. GIA never formally 'announced' they changed their grading lamps - but Marty Haske drove them nuts and I suspect it was about 15 years ago. Michaels influence would have been way less than Marty's - you can search on this forum some references from Martin. His website has disappeared - I think he is unwell. Anyone know?

I'm unclear about what point you are making. In the absence of a change in the lighting and/or procedures since 2010 then the same issue continues as illustrated and explained in detail in the Cowing study. Are you disputing any aspects of that study or the science behind it?

It is actually the science behind the study which is most relevant to the question of real world benefit to appearance of fluorescent diamonds. I have found not a single person who points to any inaccuracies in the measurements referenced or the conclusions regarding under what circumstances fluorescence is activated.

The color grading piece is actually a separate and obviously related one that has far reaching implications for the market. But I think it is just as important for consumers to understand clearly whether or not the supposed "benefits" of fluorescence are scientifically supportable.

 

[Rockdiamond]

Hi Garry,
Appreciate your participation here. Interesting points about the different devices/procedures used to grade fancy colors. I was not aware of that. It does point up the variables introduced by different light sources, devices and procedures being imployed by the labs and in the trade in assessing fluorescence. And the changes that take place that might affect consistency of grading over time.

I was also not aware that GIA has changed their color grading lamps or procedures since the Cowing study. Can you elaborate on that? Was it a response to the study?

I believe the diamond story that Michael showcased in his article that dropped 4 grades when UV light was screened out of a grading lamp was graded a long time ago. GIA never formally 'announced' they changed their grading lamps - but Marty Haske drove them nuts and I suspect it was about 15 years ago. Michaels influence would have been way less than Marty's - you can search on this forum some references from Martin. His website has disappeared - I think he is unwell. Anyone know?

I'm unclear about what point you are making. In the absence of a change in the lighting and/or procedures since 2010 then the same issue continues as illustrated and explained in detail in the Cowing study. Are you disputing any aspects of that study or the science behind it?

It is actually the science behind the study which is most relevant to the question of real world benefit to appearance of fluorescent diamonds. I have found not a single person who points to any inaccuracies in the measurements referenced or the conclusions regarding under what circumstances fluorescence is activated.

The color grading piece is actually a separate and obviously related one that has far reaching implications for the market. But I think it is just as important for consumers to understand clearly whether or not the supposed "benefits" of fluorescence are scientifically supportable.

Hi ,Bryan
All due respect but don't I qualify as a person
You're extrapolating incorrectly.
The study's purpose was to highlight inaccuracy in color grading precisely for the reasons I point to. Fluorescent diamonds have color change properties that can be seen in many lighting environments.
GIA isn't a "person" per se but they also noted the characteristic - as well as countless consumers.
In fact you're the only person I've heard dispute the color change properties.

 

[Texas Leaguer]

Hi Garry,
Appreciate your participation here. Interesting points about the different devices/procedures used to grade fancy colors. I was not aware of that. It does point up the variables introduced by different light sources, devices and procedures being imployed by the labs and in the trade in assessing fluorescence. And the changes that take place that might affect consistency of grading over time.

I was also not aware that GIA has changed their color grading lamps or procedures since the Cowing study. Can you elaborate on that? Was it a response to the study?

I believe the diamond story that Michael showcased in his article that dropped 4 grades when UV light was screened out of a grading lamp was graded a long time ago. GIA never formally 'announced' they changed their grading lamps - but Marty Haske drove them nuts and I suspect it was about 15 years ago. Michaels influence would have been way less than Marty's - you can search on this forum some references from Martin. His website has disappeared - I think he is unwell. Anyone know?

I'm unclear about what point you are making. In the absence of a change in the lighting and/or procedures since 2010 then the same issue continues as illustrated and explained in detail in the Cowing study. Are you disputing any aspects of that study or the science behind it?

It is actually the science behind the study which is most relevant to the question of real world benefit to appearance of fluorescent diamonds. I have found not a single person who points to any inaccuracies in the measurements referenced or the conclusions regarding under what circumstances fluorescence is activated.

The color grading piece is actually a separate and obviously related one that has far reaching implications for the market. But I think it is just as important for consumers to understand clearly whether or not the supposed "benefits" of fluorescence are scientifically supportable.

Hi ,Bryan
All due respect but don't I qualify as a person
You're extrapolating incorrectly.
The study's purpose was to highlight inaccuracy in color grading precisely for the reasons I point to. Fluorescent diamonds have color change properties that can be seen in many lighting environments.
GIA isn't a "person" per se but they also noted the characteristic - as well as countless consumers.
In fact you're the only person I've heard dispute the color change properties.

David,
You apparently misunderstand the information being referenced here and its implications, and you completely misstate my position. Unfortunately, it is difficult to make progress in a discussion when that happens.

 

[JEJ]

David,
You apparently misunderstand the information being referenced here and its implications, and you completely misstate my position. Unfortunately, it is difficult to make progress in a discussion when that happens.

I think I get what you're saying, and that is that florescence will not be seen in normal lighting conditions, like inside your home. Even if you use florescent bulbs in your home....the only ones that could make a difference....it's not like you're standing on a ladder viewing the stone in question 6 inches from the light bulb. That's not a normal viewing condition. If you're sitting on the couch or anything else, you won't see an effect. I agree. I has to do with what kind of bulbs you use, how many lumens said bulbs give off, ceiling heights, and all kinds of stuff, but unless you have blinding lights in your house and they are florescent bulb lights, you're not going to see anything.

The F color medium blue I just picked up....I can't see anything inside the house or even by the window. Nothing on an overcast day or even a clear hazy day. The effect only becomes 'an effect' when subjected to an UV intensity level that triggers it. On very strong and strong, it takes less UV, sure. A stone with florescence viewed in Canada on a clear summer day will look less blue than the very same stone viewed on the Gulf Coast on a clear summer day. It's about UV index.

I can walk outside right now with this medium blue F and there's not a cloud in the sky, the sun almost straight overhead and I'm in Texas, but the stone doesn't look blue or violet like a VSB would, it's sort of an icey color blue hint...you'd have to put something pure white beside it to see the blue. It's just not obvious at all and that's in the worst viewing condition possible in the real world.