Fluorescence (revisited)

[Hazarrd]

I've read through countless threads on fluorescence, but I still have a burning question.

I'ts commonly said that fluorescence can make an I stone look like an H stone (or some variant of that statement). It's also commonly said that in some cases fluorescence can cause the stone to give off a blue hue in certain lighting conditions. My question is as follows:

Assuming that the above statements are true to at least some degree, for every "ounce" (I can't think of a better unit description for color) of better color that you seen in a fluorescent stone, is there an equal "ounce" of blue hue that should be visible? The fluorescence is only activated by UV light, so I would think that the "upgrade" in stone color that you see occurs only when the fluorescence is activated by UV light. If that's true, then I would think the blue hue must also increase as the color upgrade becomes greater.

Look forward to hearing your thoughts on this!

 

[kenny]

Keep in mind fluor only happens in light that has enough ultraviolet content to activate the fluor, like in sunlight.

Under nearly all indoor lighting fluor doesn't happen.

Keep this in mind when saying blue fluor makes the color grade look closer to D.

 

[Texas Leaguer]

I've read through countless threads on fluorescence, but I still have a burning question.

I'ts commonly said that fluorescence can make an I stone look like an H stone (or some variant of that statement). It's also commonly said that in some cases fluorescence can cause the stone to give off a blue hue in certain lighting conditions. My question is as follows:

Assuming that the above statements are true to at least some degree, for every "ounce" (I can't think of a better unit description for color) of better color that you seen in a fluorescent stone, is there an equal "ounce" of blue hue that should be visible? The fluorescence is only activated by UV light, so I would think that both the "upgrade" in stone color and the blue hue that you see occurs only when the fluorescence is activated by UV light. If that's true, then I would think the blue hue must also increase as the color upgrade becomes greater.

Look forward to hearing your thoughts on this!

Good questions Hazarrd. And you are right that many things are commonly said about the visual effects of fluorescence. However, modern science does not bear out some of these commonly held notions.
Not sure if you have seen this overview in your reading:
https://www.pricescope.com/wiki/diamonds/diamond-flourescence

Contained within it it is a link to a 2010 study that demonstrates that the fluorescent effect is not activated in most normal viewing environments.

 

[Texas Leaguer]

Keep in mind fluor only happens in light that has enough ultraviolet content to activate the fluor, like in sunlight.

Under nearly all indoor lighting fluor doesn't happen.

Keep this in mind when saying blue fluor makes the color grade look closer to D.

I agree Kenny. It turns out it is a matter not only of having enough ultraviolet content in the light environment, but that it be of sufficient intensity. So even a diamond viewed in nothing but sunlight, say indoors through a window or even on a cloudy day, the intensity of the UV may not be sufficient to stimulate the fluorescence. With regard to indoor fluorescent lights, you have to hold the diamond within a few inches of the light source for the intensity to be sufficient to activate fluorescence and visual effects such as color masking.

 

[Hazarrd]

So to the extent that flourescence is activated, both the color upgrade and the blue hue are affected. But if the flourescence is not activated then the color upgrade is non-existent. True?

 

[Rockdiamond]

Here's the relevant sentence from the GIA study:
"In general, the results revealed that strongly blue fluorescent diamonds were perceived to have a better color appearance when viewed table-up, with no discernible trend table-down. Most observers saw no relationship between fluorescence and transparency."


Basically, normal room lighting contains sufficient UV content to cause a medium or strong blue stone to show some effect though the table.

I love many Medium or Strong Blue diamonds in the H-I-J-K range because they can tend to look a shade or two less yellow.
In fancy colors, it's the opposite.
Medium or strong blue in a Fancy Intense Yellow ( for example) can make the stone look a shade lighter- even in average room lighting.
Unlike a J color, looking whiter is a negative aspect for a Fancy Intense Yellow

 

[Rockdiamond]

This also supports my position that Med or strong blue will have an effect on many diamonds in "normal" room lighting-

From the PS tutorial:

"The position that GIA has taken on the issue is that UV light is present in many viewing environments, so it follows that color should be graded in realistic lighting. In making this case they have not addressed the reversal of the longstanding GIA policy that diamonds can only be color graded accurately in lighting free of UV. "

Bryan has stated modern science does not bear this out--although I have not seen definitive scientific studies declaring the lack of UV rays in normal room lighting

Hands on experience certainly shows the effect in room lighting.

 

[Hazarrd]

Thanks for pulling the excerpt. Are there any findings by GIA regarding the blue hue under these or other lighting conditions? I'm still looking for guidance on whether the "good" can only be had with the "bad".

 

[Texas Leaguer]

So to the extent that flourescence is activated, both the color upgrade and the blue hue are affected. But if the flourescence is not activated then the color upgrade is non-existent. True?

That is correct. (assuming the color of the fluoro is blue - other colors are possible)

Scientific study does not support the common claims that there is visual appearance benefit (color masking) in standard lighting environments, which is contrary to longstanding beliefs in the market, and even to the professed views of veteran members of the trade. It also calls into question the validity of certain conclusions drawn from survey results such as the one GIA conducted and which is referenced frequently.

 

[Rockdiamond]

So to the extent that flourescence is activated, both the color upgrade and the blue hue are affected. But if the flourescence is not activated then the color upgrade is non-existent. True?

That is correct. (assuming the color of the fluoro is blue - other colors are possible)

Scientific study does not support the common claims that there is visual appearance benefit (color masking) in standard lighting environments, which is contrary to longstanding beliefs in the market, and even to the professed views of veteran members of the trade. It also calls into question the validity of certain conclusions drawn from survey results such as the one GIA conducted and which is referenced frequently.

Bryan, can you copy and paste the portions of the 2010 study that support your position?

By all means it's a very interesting debate- as the characteristics of fluorescent diamonds can vary quite a bit from one stone to the next.

That makes your task a bit harder Hazzard.
There are stones that benefit from Medium or Strong blue, and others where the effect is negligible- as well as a percentage that suffer haziness due to fluorescence

 

[Texas Leaguer]

So to the extent that flourescence is activated, both the color upgrade and the blue hue are affected. But if the flourescence is not activated then the color upgrade is non-existent. True?

That is correct. (assuming the color of the fluoro is blue - other colors are possible)

Scientific study does not support the common claims that there is visual appearance benefit (color masking) in standard lighting environments, which is contrary to longstanding beliefs in the market, and even to the professed views of veteran members of the trade. It also calls into question the validity of certain conclusions drawn from survey results such as the one GIA conducted and which is referenced frequently.

Bryan, which scientific study are you referring to?

By all means it's a very interesting debate- as the characteristics of fluorescent diamonds can vary quite a bit from one stone to the next.

That makes your task a bit harder Hazzard.
There are stones that benefit from Medium or Strong blue, and others where the effect is negligible- as well as a percentage that suffer haziness due to fluorescence

David,
We have had this discussion in detail before. The Michael Cowing study is the most recent scientific work on the subject. It is the study that is referenced in the wiki I linked above. The wiki also contains a link to the GIA survey that you have quoted.

If the basic science that is described in the Cowing study is sound, then many of the statements that you and other members of the trade continue to make year after year are inaccurate and should not be presented as consumer education.

 

[Rockdiamond]

Hi Bryan,
I did look over the Cowing study, and can not find any definitive statement to back up your position.
Please copy and paste the relevant paragraphs or sentences that support what you're saying.

We have discussed this before but I don't feel we've ever reached any conclusion.
Citing a 14 page study that doesn't even support your position does not seem to be in the best interest of consumer education either

 

[Texas Leaguer]

Hi Bryan,
I did look over the Cowing study, and can not find any definitive statement to back up your position.
Please copy and paste the relevant paragraphs or sentences that support what you're saying.

We have discussed this before but I don't feel we've ever reached any conclusion.
Citing a 14 page study that doesn't even support your position does not seem to be in the best interest of consumer education either

David,
As I have encouraged you to do in the past, please do more than "look over" the study. If you want to understand the issue you need to read it thoroughly.

You and anyone else who is interested in this subject can do the same with the links provided. Having been in the trade for a longtime myself, I was also raised up with concepts on this subject which are erroneous. And I spent alot of my career believing and repeating the same myths!

 

[Hazarrd]

We're heading off on a bit of a tangent here, but are there folks out there who think the GIA study was intended to generate consumer interest in fluorescent diamonds?

 

[Rockdiamond]

We're heading off on a bit of a tangent here, but are there folks out there who think the GIA study was intended to generate consumer interest in fluorescent diamonds?

In my opinion, GIA has traditionally taken a clinical role- as opposed to trying to promote one aspect over another. That's also how I view the GIA study.
There are vendors that actively promote "blue" diamonds.
My position is not based on industry myths.
My position, garnered from over 40 years of diamond assorting, is that medium or strong blue stones can be tremendous values in all color from D-K- with easily visible benefits in the lower ranges ( I-J-K)
In the higher color ranges, the effects may be less visible, but the discounts are easy to see

Bryan, I did read the study and can't find anything to support your position.
Which is why I'm asking you to cite the parts of the study that bolster you claim.

 

[Texas Leaguer]

We're heading off on a bit of a tangent here, but are there folks out there who think the GIA study was intended to generate consumer interest in fluorescent diamonds?

Don't get me wrong, I love GIA. I have enormous respect for the organization. But it is a fact that they a huge trade constituency who support their operations. That constituency is in business and there are things that help and things that don't. GIA gets pressure to do things that help. They resist doing things that may not be helpful while making sure to stay true to their main goal of consumer education and protection. It is not an easy balancing act to perform, but they have done a superb job of it in my opinion.

 

[Texas Leaguer]

We're heading off on a bit of a tangent here, but are there folks out there who think the GIA study was intended to generate consumer interest in fluorescent diamonds?

In my opinion, GIA has traditionally taken a clinical role- as opposed to trying to promote one aspect over another. That's also how I view the GIA study.
There are vendors that actively promote "blue" diamonds.
My position is not based on industry myths.
My position, garnered from over 40 years of diamond assorting, is that medium or strong blue stones can be tremendous values in all color from D-K- with easily visible benefits in the lower ranges ( I-J-K)
In the higher color ranges, the effects may be less visible, but the discounts are easy to see

Bryan, I did read the study and can't find anything to support your position.
Which is why I'm asking you to cite the parts of the study that bolster you claim.

Better yet David, when I get time I will send you links to threads where we (you included) have already discussed this study in detail.

 

[Rockdiamond]

A lot of stuff has happened - including the devastating floods in Texas- that cut the conversation short.
Here's hoping you're safe, and that you and yours weren't hurt badly by the flooding.

But the bottom line is that to my recollection, we have not settled anything regarding this issue.
Here's the first paragraph in the Cowing study:
Abstract: Decades after the establishment in the mid-twentiethcentury
of ultraviolet-free illumination for colour grading a diamond,
an examination of diamond trade and laboratory grading practices
fi nds nearly everyone employing some type of fl uorescent tube
lighting containing signifi cant ultraviolet. This paper demonstrates
and quantifi es the over-grading of blue-fl uorescent diamonds that
often can result. Simple methods are proposed that, by themselves
or in combination, provide inexpensive and workable solutions to
resolve this problem.

What it's saying is that there's an issue in diamond color grading- precisely for the reasons I state- you'd have to try very hard to find lighting that is truly UV free.
So the point of the study is that color grading is affected by UV content in the lighting used by gem labs.
I can't find anyplace in the study that says Medium or Strong Blue diamonds don;t show effects to the UV content commonly found in indoor lighting.
The study suggests ways to eliminate the UV, but that in itself suggests that you'd need to take special steps to eliminate the UV in normal room lighting.
No?

 

[Texas Leaguer]

A lot of stuff has happened - including the devastating floods in Texas- that cut the conversation short.
Here's hoping you're safe, and that you and yours weren't hurt badly by the flooding.

But the bottom line is that to my recollection, we have not settled anything regarding this issue.
Here's the first paragraph in the Cowing study:
Abstract: Decades after the establishment in the mid-twentiethcentury
of ultraviolet-free illumination for colour grading a diamond,
an examination of diamond trade and laboratory grading practices
fi nds nearly everyone employing some type of fl uorescent tube
lighting containing signifi cant ultraviolet. This paper demonstrates
and quantifi es the over-grading of blue-fl uorescent diamonds that
often can result. Simple methods are proposed that, by themselves
or in combination, provide inexpensive and workable solutions to
resolve this problem.

What it's saying is that there's an issue in diamond color grading- precisely for the reasons I state- you'd have to try very hard to find lighting that is truly UV free.
So the point of the study is that color grading is affected by UV content in the lighting used by gem labs.
I can't find anyplace in the study that says Medium or Strong Blue diamonds don;t show effects to the UV content commonly found in indoor lighting.
The study suggests ways to eliminate the UV, but that in itself suggests that you'd need to take special steps to eliminate the UV in normal room lighting.
No?

When I finish my day job here I will try to review and distill the main points in the article as it relates to what it takes to activate the fluorescent effect and why it is not activated in normal lighting scenarios (even those containing UV). It is better not to focus on the overgrading issue before understanding that no visual effects (good or bad) can be observed without activation.

 

[Rockdiamond]

Bryan, by all means, KEEP YOUR DAY JOB
I'm looking forward to meeting you next year in Las Vegas.

 

[Texas Leaguer]

Bryan, by all means, KEEP YOUR DAY JOB
I'm looking forward to meeting you next year in Las Vegas.

Thanks David. If they let me keep my day job and there are no 100 year floods in Houston next June, I may get that pleasure. I heard you were at the GTG and met some of our team. I understand it was another good time.

 

[Rockdiamond]

Yes, it was a very good time- and your ears were probably burning as I did meet a very nice guy from your company ( whose name escapes me at this moment), and your name was bandied about in a very positive manner

Back to the subject at hand:
It seems to me that the focus of the article is overgrading of diamonds based on the UV content in the bulbs being used.
Here's a paragraph from the conclusions section of the article that supports your position. But the statement is by no means an in depth study, and I could not find other parts of the article that focused on diamonds not looking whiter than grade in normal room light.
This aspect is certainly debatable if we're basing it on this paragraph only - especially given contradicting statements by GIA IMO

In social situations, diamonds are
most commonly seen at viewing distances
of a few feet in many kinds of artificial
illumination at night or indoors away from
daylight. In these viewing environments
the UV and visible violet are too weak to
stimulate grade-whitening fluorescence.
This is in contrast to most colour grading
environments where the diamond is
typically 2 to 7 in. from fluorescent
lighting with significant UV and visible violet
components.

 

[Dancing Fire]

Thanks for pulling the excerpt. Are there any findings by GIA regarding the blue hue under these or other lighting conditions? I'm still looking for guidance on whether the "good" can only be had with the "bad".

This is how my wife's ring and my ring look indoor and outdoor under the sun. My wife's ring is a non fluor H colored stone and mine is a very strong blue fluor I colored stone.

 

[Dancing Fire]

Photos with and w/o the UV light pointing at the VSB stone.

 

[isaku5]

Wow!! ...just wow, DF.

Gorgeous two diamond family

 

[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]

 

[ariel144]

You have probably seen these, but pictures do help.

https://www.youtube.com/watch?v=G6Rgz2edN40

https://www.youtube.com/watch?v=eKDshYGBdko

https://www.youtube.com/watch?v=TVhkQ-tKVG8

Most PS'rs prefer med/strong blue fl. as it gives the diamond more personality.

Personally I love the effect.

 

[kenny]

Most PS'rs prefer med/strong blue fl. as it gives the diamond more personality.

There must have been a poll for you to make this bold claim.
I didn't notice this poll.
Do you have a link to this poll?

I think fluor is cool but prefer diamonds without it.

 

[Dancing Fire]

Most PS'rs prefer med/strong blue fl. as it gives the diamond more personality.

There must have been a poll for you to make this bold claim.
I didn't notice this poll.
Do you have a link to this poll?

I think fluor is cool but greatly prefer diamonds without it because diamonds are already hard enough for a private party to sell.

I'll take it either way b/c I don't discriminate... However, All my wife's single stones (ones with lab reports) that I have had purchased are non fluor.

 

[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.