Fluorescence-AGS question

[Paul-Antwerp]

I feel like in many cases, a bit of history may help in understanding.

In the identification of gemstones, fluorescence is one of many potential identifying characteristics. As such, checking and studying the presence of fluorescence is a standard gemological practice in trying to identify a gemstone.

Please understand: in my book, gemology is far more about identifying a gemstone, and grading the C's and other characteristics of a diamond is a minuscule side-room in the house of gemology. Sorry for the side-bar.

In that sense, the fluo-'grade' on a diamond-report in my eyes was initially mostly descriptive, meant as an identifier, just like plotting of inclusions.

Over the years however, the trade has moved to making it have influence on the value of a diamond. Whether that is correct, is hugely debatable.

And, if this thread becomes a major point of contention, I feel it has little to do with how a report is created, it far more has to do with the weird way that the trade has developed into treating fluorescence.

Live long,

 

[EvaEvans]

@Texas Leaguer
Exactly in this article that you point the final words are:
"Our findings demonstrate the diamond industry’s need for a standardized UV excitation source, to provide consistent and reproducible determinations of fluorescence."
So it is matter of standards and precise UV source. Nothing else. We are living in the 21 century!

 

[Johnbt]

If our concern as a retail buyer is whether or not an individual diamond will ever fluoresce under any circumstances, wouldn't the UV source used to check it need to emit all of the UV wavelengths and wouldn't the diamond need to be observed from every possible angle as the UV source is moved around the diamond?

It sounds like a lot of work.

From https://earthobservatory.nasa.gov/features/UVB/uvb_radiation4.php

"Ultraviolet (UV) radiation that reaches the Earth’s surface is in wavelengths between 290 and 400 nm (nanometers, or billionths of a meter). This is shorter than wavelengths of visible light, which are 400 to 700 nm."

"The incoming radiation at shorter wavelengths, 290-320 nm, falls within the UV-B part of the electromagnetic spectrum. (UV-B includes light with wavelengths down to 280 nm, but little to no radiation below 290 nm reaches the Earth’s surface)"

Of course, more UV reaches the Earth's surface if you happen to live in an area with lower ozone levels or more cloud cover, etc; so I don't know how a lab could account for that. (I suppose the entire test could be automated and initiated online and the prospective buyer could enter their zip or postal code and the computer running the test could adjust the interpretation for location, etc. And the charge for all of that? I'm guessing significant.)

Picking one UV wavelength for checking diamonds certainly appears to be no more than another way of logging an identifying characteristic to go along with weight, inclusions, height, etc. It simply says that at one or two wavelengths from one direction the diamond did, didn't, or sort of did, fluoresce.

That's how I understood it when I was diamond shopping this past April.

 

[Johnbt]

Just because it's pretty.


Now I'm off to Colonial Williamsburg for a little Christmas shopping with my wife. Luckily it's only a 30-mile drive on a scenic two-lane road.

 

[Texas Leaguer]

@Texas Leaguer
Exactly in this article that you point the final words are:
"Our findings demonstrate the diamond industry’s need for a standardized UV excitation source, to provide consistent and reproducible determinations of fluorescence."
So it is matter of standards and precise UV source. Nothing else. We are living in the 21 century!

Agree that is the goal, and has always been the goal of all labs to date. The fact is the goal has yet to be achieved. Perhaps GIA will make progress when/if they roll out the device described in the patent application that Garry posted.

 

[gemcat]

Thank you all for sharing your knowledge with me. I've learned a lot from the posts and the linked articles. I was motivated to ask the question on this forum because I could not get a reasonable answer from the "Graduate Gemologist" at the store where I bought the diamond in question. He could only tell me the company line about the stone being graded by the lab. When I pointed out to him that my UV light on my loupe showed a strong blue glow that did not jibe with the term "negligible" on the cert, his response was basically that my loupe was faulty. He could not tell me how the stone was graded at the lab, what the UV frequency used was, or any of the other points made by the posters here. I wasn't trying to be a difficult customer, but I did expect a "Graduate Gemologist" should know more than a simple customer did about the issue. Sigh, it was not the case. Again, my thanks for your willingness to share your expertise.

 

[Texas Leaguer]

If our concern as a retail buyer is whether or not an individual diamond will ever fluoresce under any circumstances, wouldn't the UV source used to check it need to emit all of the UV wavelengths and wouldn't the diamond need to be observed from every possible angle as the UV source is moved around the diamond?

It sounds like a lot of work.

From https://earthobservatory.nasa.gov/features/UVB/uvb_radiation4.php

"Ultraviolet (UV) radiation that reaches the Earth’s surface is in wavelengths between 290 and 400 nm (nanometers, or billionths of a meter). This is shorter than wavelengths of visible light, which are 400 to 700 nm."

"The incoming radiation at shorter wavelengths, 290-320 nm, falls within the UV-B part of the electromagnetic spectrum. (UV-B includes light with wavelengths down to 280 nm, but little to no radiation below 290 nm reaches the Earth’s surface)"

Of course, more UV reaches the Earth's surface if you happen to live in an area with lower ozone levels or more cloud cover, etc; so I don't know how a lab could account for that. (I suppose the entire test could be automated and initiated online and the prospective buyer could enter their zip or postal code and the computer running the test could adjust the interpretation for location, etc. And the charge for all of that? I'm guessing significant.)

Picking one UV wavelength for checking diamonds certainly appears to be no more than another way of logging an identifying characteristic to go along with weight, inclusions, height, etc. It simply says that at one or two wavelengths from one direction the diamond did, didn't, or sort of did, fluoresce.

That's how I understood it when I was diamond shopping this past April.

Yes, it is not an easy issue. It would seem to be technically possible to create a standard and develop instruments that could consistently detect and describe the identifying characteristic. Once you convinced the trade of the need to adopt the new methodology and buy the equipment, then you might begin to achieve better standardization. This is the 21st century for crying out loud! But aside from just the desire for greater scientific understanding of the property, which is a worthy goal in and of itself, one has to wonder what the actual benefit of such an initiative would be for the consumer. Particularly since other information on the lab report serve the purposes of identifying the diamond.

GIA's own observational research has shown that fluorescence, in the vast majority of cases, does not improve the appearance of a diamond's color.

https://4cs.gia.edu/en-us/blog/diamond-color-seven-things-you-need-to-know/
To answer questions from consumers and the trade about the impact of fluorescence on diamond color in the D-to-Z range, GIA conducted extensive observer testing. Here’s what its researchers found: “For the average observer, meant to represent the jewelry buying public, no systematic effects of fluorescence were detected [on the face-up appearance of the groups of diamonds]. Even the experienced observers did not consistently agree on the effects of fluorescence from one stone to the next.” As a result, GIA considers diamond fluorescence to be an identifying characteristic, not a grading factor – meaning, it has little to no impact on diamond color.

One of the things that is often overlooked in the discussion about the effects of fluorescence is that the mere presence of the wavelengths capable of causing emission alone is not enough. The intensity of those wavelengths is critical to whether emission will take place. That is why a whitening effect might be observed in direct sunlight or when a diamond is viewed within inches of a fluorescent tube, but may not be noticeable outdoors on a cloudy day or from sunlight coming through window glass. And intensity levels at the point of observation in normal overhead fluorescent lighting drop to negligible levels.

 

[Johnbt]

I'm drinking imported beer and I've been called to the dinner table...
... so I just clicked the Like button.

 

[Texas Leaguer]

I'm drinking imported beer and I've been called to the dinner table...
... so I just clicked the Like button.

Thanks for the heads up John. It's 5 o'clock here and there is a Heineken calling my name from the other room.

 

[Garry H (Cut Nut)]

So, Garry, you assume only the POSITIVE effect of the fluorescence, but I'm thinking of the possible negative effect too!
Also, when I said that 365nm or 385nm will not change the result, I was meaning that 20nm difference will not affect the existence or the absence of fluorescence. The change could be only in the level of fluorescence intensity. The important fact is that 365 is blocked by windows. 385 to 430 are not, and so they help the colour.
But I would like to know from you - what is the negative effect that so worries you? As far as i am concerned there are negative effects and they need to be picked up.
Bryan gave an excellent answer - I would only add to that - from the GIA 2013 study - multiple excitation can cause multiple colours of fluoro - blue is most commonly seen, but if there is yellow as well then that can be bad. but the blue will mask the yellow.
So, my point of thinking is, that the buyer should be trustfully informed if the fluorescence is "none" or "some", that's why I do not accept the AGS term "negligible".
Garry, if for you, as a professional in the diamond business, the UV wave length has a significant impact to the lab certification result, so why the labs don't have a standard about the measuring of the fluorescence? Why the measuring of color and clarity is standardized, but the measuring of fluorescence is not?

 

[Karl_K]

I feel like in many cases, a bit of history may help in understanding.

In the identification of gemstones, fluorescence is one of many potential identifying characteristics. As such, checking and studying the presence of fluorescence is a standard gemological practice in trying to identify a gemstone.

Please understand: in my book, gemology is far more about identifying a gemstone, and grading the C's and other characteristics of a diamond is a minuscule side-room in the house of gemology. Sorry for the side-bar.

In that sense, the fluo-'grade' on a diamond-report in my eyes was initially mostly descriptive, meant as an identifier, just like plotting of inclusions.

Over the years however, the trade has moved to making it have influence on the value of a diamond. Whether that is correct, is hugely debatable.

And, if this thread becomes a major point of contention, I feel it has little to do with how a report is created, it far more has to do with the weird way that the trade has developed into treating fluorescence.

Live long,

Well said and worth repeating!

 

[EvaEvans]

@Johnbt
The common and widely adopted UV wave length in gem identification is 365nm.
The GIA article also shows that the tested diamonds have a pic of fluorescence emission at 365nm.
What labs have to do is to standardize their UV source and synchronize their terminology about fluorescence grading.

 

[EvaEvans]

Thank you all for sharing your knowledge with me. I've learned a lot from the posts and the linked articles. I was motivated to ask the question on this forum because I could not get a reasonable answer from the "Graduate Gemologist" at the store where I bought the diamond in question. He could only tell me the company line about the stone being graded by the lab. When I pointed out to him that my UV light on my loupe showed a strong blue glow that did not jibe with the term "negligible" on the cert, his response was basically that my loupe was faulty. He could not tell me how the stone was graded at the lab, what the UV frequency used was, or any of the other points made by the posters here. I wasn't trying to be a difficult customer, but I did expect a "Graduate Gemologist" should know more than a simple customer did about the issue. Sigh, it was not the case. Again, my thanks for your willingness to share your expertise.

The loupe's UV single led is the most UNRELIABLE source of UV light! First, it is too weak, second, you should have some distance from the UV light to the stone. Better buy a professional UV lamp or at least powerful LED UV flashlight. Also, it is much better to have a non-fluorescent diamond for comparison, especially if you don't have experience.

 

[Karl_K]

@Johnbt
The common and widely adopted UV wave length in gem identification is 365nm.
The GIA article also shows that the tested diamonds have a pic of fluorescence emission at 365nm.
What labs have to do is to standardize their UV source and synchronize their terminology about fluorescence grading.

That 365 was adopted does not mean it is right.
365 was adopted because it was available.
Lets say there was a source available that was only 365nm and no other light period.
A diamond has no florescence under it.
Does that mean the diamond has no florescence?
Nope, it just means it does not at 365.....
It is an eye opened when you hold a diamond that under sunlight is clearly florescent but under standard grading lighting has none but under a bunch of different uv sources ranges from very strong to none.

 

[Diamond_Hawk]

@Johnbt
What labs have to do is to standardize their UV source and synchronize their terminology about fluorescence grading.

Why?

The posters here have just detailed, in thousands of words, all the variables that come into play for diamond fluorescence. Every lab using the same source and same terminology would, then, necessarily limit the description of FL to identical standards (through subjective, human interpretation)?

As technology improves there will be better and more accurate ways to describe every characteristic of a diamond. Grading labs who are competing for business will always seek ways to gain more customers. If AGSL and GIA differ in their methodologies, that allows more choice for consumers. If one lab starts to out-pace the others in a particular area, it will be noticed and the other labs will adapt and improve; everyone will be better for it.

 

[EvaEvans]

@Diamond_Hawk
If the labs were permitted to use whatever terminology they like, then their certificate will not be certificate!
It is obvious that you don't understand what "standard" mean and why in the science the standards are so important! There will be NO science without standards! For example, do you know what "standard measurements" mean? Fahrenheit or Celsius is the standard scientific measurement for temperature? Why diamonds are measured in mm, not in inches? Because millimeter is scientific dimension!
Why D-Z color, not other terminology? Why IF-VVS-VS-Si-I clarity? Because they are standards in the diamond industry, right?

 

[EvaEvans]

@Karl_K
To be any scientific experiment lеgitiment, the examination has to be made within specific conditions. As the 365nm as widely adopted for fluorescence measurement, there is a reason for that.
Also, as already mentioned, above 400nm is the visible light, so we cannot cal UV any light wave above 400nm.

 

[EvaEvans]

In this discussion I clearly see one mistake that is made.
On one part, you comment what you see what you eyes, on the other: the scientific (technical) measurements.
Here many of you are discussing the fluorescence's IMPACT (mostly to the color), but not the fluorescence PRESENCE.
OK, as the measurement of the diamond color requires certain conditions (full WHITE spectrum of light), as the fluorescence measurement requires certain conditions (365nm).
Obviously, the diamond color will change if we observe it on different background or under NON-lab light, for example day summer light, day winter light, indoor incandescent light (different bulbs will give different result), candle light, etc.
So it is obvious, the fluorescence will do the same: will be there at 365nm or not, will change its color in different wave length, or will not, will be less or more if we change the conditions, right? But if the standard is 365nm, so this should be on the lab report. If the diamond business agree on something different, than OK, but till then, the 365nm is the standard!

 

[Karl_K]

OK, but till then, the 365nm is the standard!

Check the specs, thoughts?
https://www.gia.edu/doc/GIA_UV_Lamp_and_VC_User_Guide_English.pdf

 

[Johnbt]

"For example, do you know what "standard measurements" mean? Fahrenheit or Celsius is the standard scientific measurement for temperature?"

Do I? Well yes, I do.

And you've forgotten the Kelvin scale. Named after William Thompson, 1st Lord Kelvin

"The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics. The kelvin is the base unit of temperature in the International System of Units.- Wikipedia"

John (who once upon a time was a physics major.)

 

[Karl_K]

As long as AGSL and GIA are not using the same terms to mean different things then I dont see a huge problem with how it is reported on the report.
The question could be asked if AGSL should match gia and add a none category?
Honestly I think the AGSL wording is more honest. Because gia none leads one to believe there is none which is not always the case.
GIA "none" is no guarantee that the stone is not reactive to UV as the wording implies.

 

[Karl_K]

Check the specs, thoughts?
https://www.gia.edu/doc/GIA_UV_Lamp_and_VC_User_Guide_English.pdf

Geek stuff follows, you have been warned :}

According to the pdf file:
The 365 nm UV LED incorporated into the GIA UV Lamp and Viewing
Cabinet has a single emission at 365 nm with a FWHM (Full Width at Half Maximum)
value of 9 nm. The state of the art appears to be 2.5nm FWHM.

What that means in English is the light output should be at 1/2 power within 9nm centered at 365nm.
That is a long way from pure 365 but light years ahead of the common 10 cent emitters if it is driven correctly.
How they are driven can change the FMHM as can temperature.
There is not enough information to find the specific emitter and get the spec. sheet.
I did find some in the general area and they were not cheap. $40 and up each in low quantities.
And...
$849.00 https://store.gia.edu/product-p/533000.htm
If they are actually used in the lab is unknown.

Interesting reading:
https://www.gia.edu/gems-gemology/summer-2013-luo-fluorescence-optical-defects

 

[Garry H (Cut Nut)]

@Johnbt
The common and widely adopted UV wave length in gem identification is 365nm.
The GIA article also shows that the tested diamonds have a pic of fluorescence emission at 365nm.
What labs have to do is to standardize their UV source and synchronize their terminology about fluorescence grading.

Dear Eva,
1. The UV used to ID gems is a standard for a different purpose. It is wrong for the fluoro effect with diamonds.
2. Labs issue Reports not Certificates. Big difference.
3. 365 creates very little Fluorescence and since that is what we are studying simple and variable cheap visible UV tools are more relevant than 365nm because there is very little 365 in human environments vs there is heaps of the UV and visible violet that create the most N3 excitation.
From https://www.gia.edu/gems-gemology/summer-2013-luo-fluorescence-optical-defects
(I added the black line at about 365nm and the purple line to indicate that the energy that contributes the most is way way above 365nm and well into the visible spectrum).

 

[EvaEvans]

@Garry H (Cut Nut)

Fluorescence (bottom left)
The maximum fluorescence emission is shown on the bottom left graphic (the blue line). It is clearly visible that the maximum pick is at 365nm.
The bottom right graphic (red line) shows the PLE (photoluminescence excitation).

 

[EvaEvans]

I will repeat again: what should be on the lab report, is the FACT, not the opinion.
Term "negligible" is misleading, because it is an opinion of the lab, not a fact!

Although this is not connected with this thread, but improper and outdated terms are still in use in the lab "reports". For example, I even don't look at the "cut grade", because this is an OPINION of the lab, not a FACT. Much more relevant to me is the symmetry and the polish grade. "Shape and cutting style" also has to be modified, because term like "Circular brilliant" is again, an opinion, but not fact! What is fact is that the stone is round!

 

[EvaEvans]

@Johnbt and @Karl_K
It is obvious that you don't have a clue how the scientific lab exam has to me made and what the requirements are!
Well, I have engineer degree.
I know what "technical accuracy" mean! Every technical equipment has to have specific accuracy. As more precise is the accuracy, as more expensive is the equipment, but it is not necessary always the accuracy to be in tight range. The accuracy depends of the purpose.
@Karl_K
As for the purpose, the GIA UV lamp accuracy is in 9nm range (+ and -). This specific accuracy will NOT change the result in examination of the fluoresce, then!
@Karl_K
It is not what you "like", but what is scientific to be on the lab report! GIA "none" means EXACTLY this: there is NONE of visible fluorescence at 365nm! Obviously, at other UV length the result could be different. AGS "negligible" does not mean "none" or "some", so AGS fluorescence result is useless.

 

[Paul-Antwerp]

Eva,

With all due respect, and not trying to be funny.

But if you are looking for 'FACTS' on a diamond-report, here are the only facts:

- The date of the report (although some would state that this could be debated)
- The weight of the diamond
- The fact that the diamond is natural and untreated (although some could argue that technological advances in synthesis and/or treatment could possibly lead to them not being detected by a lab)

Seriously, that is it, with regards to facts.

Live long,

 

[Texas Leaguer]

I will repeat again: what should be on the lab report, is the FACT, not the opinion.
Term "negligible" is misleading, because it is an opinion of the lab, not a fact!

Although this is not connected with this thread, but improper and outdated terms are still in use in the lab "reports". For example, I even don't look at the "cut grade", because this is an OPINION of the lab, not a FACT. Much more relevant to me is the symmetry and the polish grade. "Shape and cutting style" also has to be modified, because term like "Circular brilliant" is again, an opinion, but not fact! What is fact is that the stone is round!

The term 'negligible' is not misleading, despite the fact that the definition may be commonly misunderstood. The term has a meaning separate and distinct from the term 'none'.

negligible: adjective
too slight or small in amount to be important.
(E.g. "the effect on sales was negligible.")

In this context it can be argued that it is more accurate to describe diamonds with little or no fluorescence as negligible, than to describe a diamond tested at a specific wavelength as having 'none' when it is known that other wavelengths can potentially stimulate fluorescence of varying degrees and colors.

 

[lovedogs]

@Johnbt and @Karl_K
It is obvious that you don't have a clue how the scientific lab exam has to me made and what the requirements are!
Well, I have engineer degree.
I know what "technical accuracy" mean! Every technical equipment has to have specific accuracy. As more precise is the accuracy, as more expensive is the equipment, but it is not necessary always the accuracy to be in tight range. The accuracy depends of the purpose.
@Karl_K
As for the purpose, the GIA UV lamp accuracy is in 9nm range (+ and -). This specific accuracy will NOT change the result in examination of the fluoresce, then!
@Karl_K
It is not what you "like", but what is scientific to be on the lab report! GIA "none" means EXACTLY this: there is NONE of visible fluorescence at 365nm! Obviously, at other UV length the result could be different. AGS "negligible" does not mean "none" or "some", so AGS fluorescence result is useless.

This is very rude, and overall an ignorant statement. The trade people on this forum like @Karl_K know a great deal about the history of stones, grading, etc. Just because you don't like how flour ia graded doesn't mean you can be rude.

 

[Paul-Antwerp]

In follow-up of this thread, I asked my team to check fluo on all GIA-None passing by in our office, and to photograph whenever there was fluo, despite the grade being None. Literally, the first stone passing our office today already was bingo.

GIA-report-number is 2141960645, https://www.gia.edu/report-check?reportno=2141960645&s=1544456425618

And this is the pic, borderline Medium according to our internal assessment


Live long,