Should we discourage or recommend FL stones?

[Rockdiamond]

Hi everyone!
In a recent discussion a poster asked about a stone with fluorescence.
There’s a lot of strong opinions on this and a comment was made that implied some participants were doing a disservice by recommending fl stones.

I very much disagree with that sentiment but I do find that this particular aspect of diamond assessment is both important and widely misunderstood.

Here’s where I stand on this issue:
I won’t ever make blanket statements about how fluorescence affects a particular diamond that I’ve never seen.

I heard an interesting joke that relates to this discussion.
A guy boarding a plane asks the captain-
"How often do planes crash?"
His answer-
"Usually about once"

My point is, statistics are not really important to any specific diamond. One strong blue might be a dud and the next a sparkler.
Plus, fluorescent diamonds use light in ways that is difficult if not impossible to capture on video or still photos.
So trying to asses remotely seems impossible.

To add to the “interesting” nature of this discussion is the fact that some of the tradespeople that participate don’t agree on some basics such as what can “set off” a fluorescent diamond.
Even if we disagree on some of the specifics I'd bet Bryan and the majority of tradespeople would agree that in person, hands on assessment is the only reliable means of judging how fluorescence affects the majority of diamonds that possess this characteristic.

What’s your thoughts, or questions?

 

[Karl_K]

When in doubt give them the facts and let them decide themselves.
If the facts are incomplete explain both sides of the opinions.

 

[Karl_K]

Part of the problem in coming to terms with it is definitions.
Some people feel that the very act of turning blue makes it milky/oily even if the virtual facets can be seen just as clear and crisp as it does in no uv light.
To me they are just fine and I like the effect.
There are other stones that are milky/oily that I do not like.
Looking at them the difference is clearly and very visible.
Some people put both types in the same group.
I think that is not correct but that is my opinion.

Colored diamonds is another kettle of fish in which the effects are super variable.
If paying a high premium for a highly yellow diamond you want to see that yellow not blue.

I think it is a fact that lab florescence is not an accurate assessment because they are using the wrong wavelength.
They should be using 400nm.

 

[Rockdiamond]

Great point Karl!
l agree that definitions are a problem in this regard.
Even to the extent of the grades themselves. Sometimes a stone graded "Faint" has a teeny bit of fl, and other times it really looks like it should have been called medium blue.
So the act of specifying the exact amount of fluorescence a diamond possesses is nothing at like an exact science.

Colored diamonds is another kettle of fish in which the effects are super variable.
If paying a high premium for a highly yellow diamond you want to see that yellow not blue.

This is a huge one.
Fluorescence in yellow diamonds is a massive consideration- it's much more likely to be an issue in a yellow diamond.
So many MB and SB stones we see are immediately rejected by us- when there is one, it's very easy to see the problem.
BUT- it also has the opposite effect on certain diamonds.
Sometimes a Fancy Yellow with MB faces up just like a Fancy Intense Yellow....I believe the difficulty in grading has to do with the lighting used by GIA. In other words, in the lab- with whatever UV is present at the lab- a fl yellow diamond looks less yellow than in "normal" lighting.

Other colors present totally different considerations......

 

[Wewechew]

I prefer stones with florescence... so I don't really see how this is an issue as long as the buyer understands the small risk and evaluates the stone when they have it in hand.

The other thread left me

 

[Rockdiamond]

I prefer stones with florescence

So do I!
I love many of them.
But I can guarantee you that we can find fluorescent diamonds that the vast majority of diamond buyers would reject.
Even those that love fluorescence in diamonds. Even you ( most likely

 

[denverappraiser]

The vast majority of people spend the vast majority of their time under lighting with zero UV component. UV has no affect. Incandescent, LED, halogen, argon, and most commercial fluorescent lighting all come in at barely detectable. Sunlight filtered through most glass has rather little. Shaded sunlight has close to none. Direct, unclouded sunlight is the issue, and even with that, most diamonds below Very Strong have no visible effect. This may not matter, it's a 'mind clean' topic, and if it bugs you that's a reason to avoid them, but it can have a very real effect on the price. Everyone is interested in that.

 

[Rockdiamond]

Incandescent, LED, halogen, argon, and most commercial fluorescent lighting all come in at barely detectable.

Shaded sunlight has close to none. Direct, unclouded sunlight is the issue, and even with that, most diamonds below Very Strong have no visible effect.

Maybe in Denver, but not here in NYC Neil.
I can spot MB, SB and even some faint fl stones in "normal" fluorescent room lighting, no direct sun.
Indirect, or cloudy skies will indeed light up certain fluorescent diamonds. This is definitely NOT a mind clean issue.

 

[Texas Leaguer]

To put in perspective the relative intensity of direct sunlight vs sunlight through a window vs overhead flurorescent lighting vs fluorescent desk lamp, I took the following readings this morning.

In the direct sunlight photo the sun is lightly diffused by some high altitude clouds. On a cloudless day the intensity would have exceeded the capacity of the meter (1,999). Two outdoor shots are shown, one pointing the meter directly at the sun and the other in indirect sunlight.

The lamp readings are taken at distances of approximately 2 inches and 10 inches from the tubes. And a third shot with the lamp off and only the overhead daylight fluorescent tubes on.

The window photo is north facing.

You can how direct sunlight is magnitudes more intense than anything indoors. And you can see how in indoor overhead lighting the intensity drops of dramatically within a few inches of the light source, and is negligible to overhead lighting.

 

[Rockdiamond]

I've also done meter testing.
The problem is, the darn diamonds don't know how to use or respect that meter

 

[Rockdiamond]

@Texas Leaguer ....
Can we focus on the values I'm sure we share.
Fluorescent diamonds must be evaluated in person.
Fluorescent diamonds can be beautiful.
Looking at where we differ can also be positive- because we'd likely also agree that love and appreciation of diamonds is an intensely personal thing.
I love the fact that diamonds are so individual. A given D color may strike me as whiter than white. Some J colors look tinted and others appear colorless. This is true even for inert stones- and fluorescent ones too. The traits we love about diamonds won't necessarily be the same. Nor will the way we look at them.
We'll never agree on how much fluorescence can affect a diamond and under which conditions.
And I'm still very glad we have the ability to discuss it. I have learned much reading your posts.

 

[kenny]

Don't encourage or discourage.

Rather, educate thoroughly and fairly (with no regard to how what you say affects your businesses's profitability (a challenge for many in business) and the customers will make their own decisions.

 

[Texas Leaguer]

I've also done meter testing.
The problem is, the darn diamonds don't know how to use or respect that meter

That is of course a different device. A lux meter measures the quantity or brightness of light. You can have very bright light sources with no UV component.

 

[Texas Leaguer]

As @kenny suggests, the aim should be to educate, not persuade. But the science suggests very strongly that in the vast majority of indoor lighting environments there is insufficient UV intensity necessary to stimulate emissions. Therefore, most consumers will experience neither transparency deficits nor potential color whitening due to fluorescence. GIA has always stated that fluorescence is not a grade, it's a description that helps to identify the diamond.

If you like the fact that your diamond glows under a black light (a pretty cool thing), especially if you can get a discount, then a fluoro diamond may be just right for you. Just don't predicate your purchase on the supposed benefit of color whitening (or be fearful of transparency issues), unless you will be viewing your diamond in bright sunlight a good deal of the time.

 

[Rockdiamond]

Bryan- I stressed the aspects upon which we surely agree above.
1) hands-on assessment is a must
2) fluorescence, in itself, does not make a diamond undesirable, necessarily.
I take offense to anyone saying my questioning the science upon which your points are being made has anything at all to do with giving up my commitment to education. That is precisely why I question that science.
My real-life experience does not agree with the conclusions.
We agree that people buying a J color should be well aware, it's a J color- regardless of Fluorescence.
I have seen my share of stones with transparency issues related to Medium or Strong Blue, therefore I do not agree with a blanket dismissal of concern regarding transparency issues- see point 1- hands-on is necessary with Medium or Stong Blue.

I'm not suggesting people buy or not to buy any given diamond based on fluorescence. Many people ask for it specifically. Many people specifically request not to see fl stones.
We serve either best we can.
Bryan, I'm sure you do the same.

 

[TODiamonds]

This is a great thread.

I don't really have a position on whether anyone should buy or avoid flo diamonds. Beauty is in the eye of the beholder, and if you dig it and get a sweet discount than why not?

I think it is irresponsible when people throw around that 0.2% GIA statistic which is obviously incorrect and misleading. It sends the absolute wrong message - that statistically it is almost impossible for a fluorescent diamond to exhibit milkiness - when in reality almost every experienced dealer I've talked to strongly feels otherwise.

Based on my own limited testing (which is nowhere near as large a sample size as any dealer), using direct sunlight, my observation has been that strong/very strong fluo diamonds exhibit milkiness in 15-20% of cases if I had to ballpark. Many dealers believe it's even higher. Most of the instances I've noticed it are reasonably subtle but still noticeable - and once I've seen it then I can't unsee it, personally. I would guess most "normal" consumers wouldn't even notice.

At the end of the day, 100% - see it in person under direct sunlight if that's an option. HOWEVER the reality is that most people on this forum are online shoppers who will not have the option to do that. And I personally wouldn't trust the word of a salesperson from BN/JA over the phone either.

The other factor is that regardless of personal taste, market prices are market prices - so those thinking they are "getting a deal" on a flo diamond will most likely be very disappointed in the value they receive if they ever want to sell or upgrade in the future.

 

[Dancing Fire]

At the end of the day, 100% - see it in person under direct sunlight if that's an option. HOWEVER the reality is that most people on this forum are online shoppers who will not have the option to do that. And I personally wouldn't trust the word of a salesperson from BN/JA over the phone either.

neither would I, b/c their stones aren't inhouse. Here's my old VSB Octavia under the sun. Does it look hazy to you?

 

[Texas Leaguer]

Bryan- I stressed the aspects upon which we surely agree above.
1) hands-on assessment is a must
2) fluorescence, in itself, does not make a diamond undesirable, necessarily.
I take offense to anyone saying my questioning the science upon which your points are being made has anything at all to do with giving up my commitment to education. That is precisely why I question that science.
My real-life experience does not agree with the conclusions.
We agree that people buying a J color should be well aware, it's a J color- regardless of Fluorescence.
I have seen my share of stones with transparency issues related to Medium or Strong Blue, therefore I do not agree with a blanket dismissal of concern regarding transparency issues- see point 1- hands-on is necessary with Medium or Stong Blue.

I'm not suggesting people buy or not to buy any given diamond based on fluorescence. Many people ask for it specifically. Many people specifically request not to see fl stones.
We serve either best we can.
Bryan, I'm sure you do the same.

You shouldn't take offense RD. You started the thread and asked for everyone's thoughts.

When you say you are questioning the science, exactly what science do you think is in question?

 

[diamondseeker2006]

I think fluorescence is beautiful, but even when I had a strong blue, I never really saw the fluorescence unless I used a UV light. I avoid low clarity stones, period, and I would discourage someone from buying a low clarity fluorescent stone from a drop shipper, because it seems those may have a higher likelihood of being hazy. I don't even have one at the moment (other than my original ering stone), but given two identical stones with one having fluorescence, I'd choose the fluorescent one.

I think the seller has to cater to the buyer. Some people are convinced that fluorescence is bad since some jewelers have said so. Some may plan to later sell a stone, so they need to take into consideration that it may be harder to sell. Others like me request them because of their beauty and they often come with a price discount. If I had a large amount of excess money, I'd buy some just to collect!

 

[Rockdiamond]

As @kenny suggests, the aim should be to educate, not persuade. But the science suggests very strongly that in the vast majority of indoor lighting environments there is insufficient UV intensity necessary to stimulate emissions.

Hi Bryan,
The reason I took offense is the implication that this thread- or my participation is intended to do anything other than educate for the sale of education itself.
In terms science- you’re the one claiming science Proves your point in this thread. Which science proves your point?

 

[denverappraiser]

I think the answer to the question is no, we shouldn't discourage or recommend FL stones. It depends on the details.

They're cool, if you like it. FWIW, I do. Others don't. That's a difference in the customer, not the stone.

Under most viewing environments it has no visible effect. This too differs and the difference has to do with the customer and the sorts of lighting environment they're in.

It often affects the price, sometimes in a big way. This one is curious. Everybody likes low prices, but people often equate more expensive and better. In effect, some people prefer high prices. As with the above, this has more to do with the customer than the stone. It's perhaps worth noting that it's not related to whether a particular stone is a 'good deal'. It might be, but it might not. If it bugs you, don't buy it. The right price on the wrong thing is no bargain. If you love how it looks at the disco and the tanning salon, a strong FL may be the stone for you.

 

[Texas Leaguer]

There is plenty of discussion already in the forum archives regarding the science (and myths) of fluorescence. The thread below goes on for 22 pages for anyone interested in taking a rather uneven journey.

Article - Over Grading of Blue Fluorescent Diamonds Revisited

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

www.pricescope.com

Here is a GIA article with some modern science:

Fluorescence Produced by Optical Defects in Diamond: Measurement, Characterization, and Challenges | Gems & Gemology

How variations in UV lamp output can affect observed fluorescence color and intensity.

www.gia.edu

And here is the bottom line from GIA on the notion of real world whitening due to blue fluorescence:

Can an average person tell the difference between diamonds that do and don’t fluoresce?
GIA has studied the effect of blue fluorescence on diamond appearance. The Institute screened a large number of diamonds, assembling four sets of six diamonds, with each group representing a different color grade (E, G, I, and K). The diamonds in each set were as similar as possible in all respects except the intensity of blue fluorescence. Diamond graders, trained professionals, and average observers viewed the diamonds in controlled conditions to make a judgment about their appearance.
Here is what GIA found: “For the average observer, meant to represent the jewelry buying public, no systematic effects of blue fluorescence on the face-up appearance of the groups of diamonds were detected. Even experienced observers did not consistently agree on the effects of fluorescence from one stone to the next.”
Simply put, blue fluorescence had a negligible effect on the face-up appearance of diamonds in the colorless or near-colorless grade ranges (grades D through J) except for a slight improvement in the rare instances of very strong fluorescence intensity.

Is Diamond Fluorescence Good or Bad?

What is diamond fluorescence? Should you buy (or not buy) a diamond because of it? GIA sheds some light on this often misunderstood phenomenon.

4cs.gia.edu

 

[oldminer]

Rockdiamond, it might be enlightening for consumers to better understand your estimate of the percentage of just the dealers you know who strongly resist or avoid buying diamonds with more than slight UV fluorescence.

While experts are divided as to how to react to a fluorescent diamond, most of us are smart enough to say every consumer has the right to love and buy what they wish. Dealers like you often believe this is true, but they spend their money with great caution. Is it wrong for consumers to understand that in the long term every diamond ends up being re-sold, usually back into the diamond trade, where dealers want problem free diamonds. They haggle and often refuse to buy a diamond with some characteristic which "might" tie up their money for longer than some other diamond lacking that "problem characteristic"?

Do you think that this widespread tendency of the way dealers react to UV fluorescence is pretty much the norm in spite of any arguments we might make here? Do you see any move from your traditional dealer buddies to greet fluorescent diamonds in a more generous or understanding manner? You may be personally liberal after all your exposure to Pricescope for so long, but I believe you would be exceptional among the majority of dealers. I see this issue mostly as a battle over tradition, not a battle based on scientific facts. What do you think?

 

[Rockdiamond]

Really excellent points by David, Neil, and Bryan....I'd like to respond a bit later to them specifically...
Meantime....
I believe that we all agree that any informed diamond seller, gemologist, appraiser, etc should never make a blanket statement about fluorescence being "good" or "bad".
In the case of sellers in particular- it seems we all agree that it's our job to serve and educate the client. Regardless if they want fluorescence or not.

I agree that some sellers would use this confusion to their advantage by claiming advantages that are not real. Unfortunately, our business is populated with a percentage of sellers who place sales numbers over truthfulness. Any blanket claims of fluorescence "helping" or "hurting" a diamond are ill-conceived.
We're probably all in agreement so far ( I hope)

But that does not mean that there are not cases where fluorescence actually hurts or improves a diamond's appearance.
I have seen such cases, and many times over many years.
I've personally seen many cases J color stones, that looked whiter due to fluorescence, out of direct sunlight
I've personally inspected large parcels, out of direct sunlight, where certain fluorescent diamonds immediately stood out.
more coming......

 

[Rockdiamond]

There is plenty of discussion already in the forum archives regarding the science (and myths) of fluorescence. The thread below goes on for 22 pages for anyone interested in taking a rather uneven journey.

Article - Over Grading of Blue Fluorescent Diamonds Revisited

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

www.pricescope.com

Hi Bryan,
Why did that thread go on for so many pages?
The reason is that there is NO consensus that Micheal's work is accurate- and I was not the only one stating this. When he was pressed, he simply changed the subject. This is NOT a scientific peer-reviewed study. Below was a post from the very first page. I'm by no means alone in the experience of certain fluorescent diamonds facing up whiter than the GIA grade, which is obtained through the pavilion.

High Bryan, in other discussions with you I posted references to this article - I just found it and posted a searchable note in an edit one post above yours.
You will note that there is quite a lot of N3 blue excitation possible from visible frequency light - not just VV and invisible UV wavelength radiation. So, may I rest my case? That blue fluoro can and does improve face up color of many if not all strong blue fluoro diamonds in almost all lighting that is adequate to determine slight (1-2 grade) color differences.

I stated out the outset- you and I will never come to an agreement on this specific aspect, and that's perfectly ok.

 

[TODiamonds]

neither would I, b/c their stones aren't inhouse. Here's my old VSB Octavia under the sun. Does it look hazy to you?

In all honesty I can't tell from a pic. I need to see it in person and move it around.

 

[Rockdiamond]

Here is a GIA article with some modern science:

Fluorescence Produced by Optical Defects in Diamond: Measurement, Characterization, and Challenges | Gems & Gemology

How variations in UV lamp output can affect observed fluorescence color and intensity.

www.gia.edu

Hi Bryan,
Please show me where this article says anything at all to back up your claim that fluorescence is never excited outside of direct sunlight

 

[Rockdiamond]

Hi again Bryan, Next:
This page links to this one
Here's the paragraph from that page.

Some gem diamonds fluoresce, most commonly blue, to the concentrated long-wave ultraviolet radiation of a UV lamp. There is a perception in the trade that this fluorescence has a negative effect on the overall appearance of such a diamond. Visual observation experiments were conducted to study this relationship. Four sets of very similar round brilliant diamonds, covering the color range from colorless to faint yellow, were selected for the different commonly encountered strengths of blue fluorescence they represented. These diamonds were then observed by trained graders, trade professionals, and average observers in various stone positions and lighting environments. For the average observer, meant to represent the jewelry buying public, no systematic effects of fluorescence were detected. Even the experienced observers did not consistently agree on the effects of fluorescence from one stone to the next. 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.

If you read this, it supports BOTH of our positions.
For you:
For the average observer, meant to represent the jewelry buying public, no systematic effects of fluorescence were detected.

Yet the article contradicts itself with the following two sentences:
1) Even the experienced observers did not consistently agree on the effects of fluorescence from one stone to the next.
What this means, to me is that there is never going to be a consensus

2)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.
GIA grades colorless diamonds through the pavilion. This means two stones which look the same color from the bottom ( pavilion) can, and do face up differently due to fluorescence.

 

[Texas Leaguer]

Hi Bryan,
Please show me where this article says anything at all to back up your claim that fluorescence is never excited outside of direct sunlight

I did not say that David.
Clearly it is possible to stimulate fluorescence if you place the diamond within a few inches from a UV tube light.

 

[Rockdiamond]

Let's try it this way Bryan-
Do you believe there are MB and SB stones graded J color by GIA that face up whiter than inert J color stones when the stones are viewed in lighting bright enough to perceive color?
I've seen countless such stones over the years.

In the 23 page thread so many possible causes to the differences we see were explored. Which is why I think that the best thing for you and I to do is to agree to disagree.
We agree on so many other important aspects of this discussion.