Have you ever tested your "negligible" AGS stones for fluorescence?

[Dancing Fire]

As I understand it AGS negligible can be a faint blue stone?. Not that I mind a faint blue stone but so far I haven't came across one yet.

 

[Texas Leaguer]

DF,
The AGS category of negligible includes both none and faint. Therefore, you potentially have stones that are almost medium.

Many people are not aware that even the GIA category of none can have stones with some fluorescence, just not enough to fit their definition of faint.

We see examples of both fairly regularly.

 

[Karl_K]

Yea with either lab if you want none you have to have your vendor check for you.
Even then there is a chance it will react to other wavelengths of UV so it has to be checked in sunlight and it can be bright enough to cover up some so you really can't be 100% sure it will never react to UV.

 

[diamondsR4eVR]

Interesting. I didn’t know that. I just ordered a pair of AGS studs that said negligible. I’m totally ok if it has it tho. I will test with my blacklight when they come in.

 

[Texas Leaguer]

Interesting. I didn’t know that. I just ordered a pair of AGS studs that said negligible. I’m totally ok if it has it tho. I will test with my blacklight when they come in.

Be aware that depending on the type of blacklight you use, your observations may be different from those done at the lab.

See section called Fluorescence Assessment by Jewelers and Appraisers at the link below.

Is Diamond Fluorescence Good or Bad?

What is diamond fluorescence and how does it affect the look and price of the diamond? Find out answers to all this questions with this guide.

www.whiteflash.com

 

[Tekate]

Nope. I don't even remember if my ACA has negligible fluor!

 

[Texas Leaguer]

Nope. I don't even remember if my ACA has negligible fluor!

Yep. ACA has always required negligible fluorescence as defined by AGS.

 

[Rockdiamond]

Bryan- you're giving useful information right here. Yet you continue to link to the article on your website which then links to a debunked study and uses conclusions we know to be erroneous.
It's just plain wrong and a disservice to the readers.

 

[Texas Leaguer]

Here are some interesting images of GIA and AGS diamonds with varying strengths of blue fluorescence, including a couple of dual certified stones.

 

[Texas Leaguer]

Bryan- you're giving useful information right here. Yet you continue to link to the article on your website which then links to a debunked study and uses conclusions we know to be erroneous.
It's just plain wrong and a disservice to the readers.

There are two studies linked in the article. One is a GIA study, and the other is the Cowing study that is also linked in the pricescope knowledge base. Neither one has been 'debunked'.

 

[Stephan]

Yes, I have tested on three of my AGS negligible diamonds.
One of the three was faint/medium.
And it was the less attractive one.
People looking at diamonds in their office won't notice it.
Under strong spot lighting, it becomes more evident.
IMHO, fluorescence affects transparency/fire/the material.

 

[AV_]

I've been applauding fluorescence as a qulity independent of cut. It seems reasonable enough to not want any of it in optical crystals.

 

[sledge]

Yes, I have tested on three of my AGS negligible diamonds.
One of the three was faint/medium.
And it was the less attractive one.
People looking at diamonds in their office won't notice it.
Under strong spot lighting, it becomes more evident.
IMHO, fluorescence affects transparency/fire/the material.

Haha, you're about to turn @Rockdiamond's world upside down.

 

[Rockdiamond]

Not at all @sledge
I enjoy discussing diamonds in a way that dispels incorrect assumptions.
I totally get why @Stephan wrote what they did.
Without a doubt, certain MB or SB diamonds show subtle negative aspects compared to their inert brethren. In really bad cases the transparency issues are readily apparent. In some cases there’s no transparency issue whatsoever. And there’s many stones in the middle.
Sometimes an ever so slight deterioration in transparency in return for a white looking J color.
But by no means is it true that every MB/ SB suffers transparency issues.

 

[the_mother_thing]

I’d appreciate recommendations for a good (but not crazy-expensive) blacklight light to test with ... like a penlight style. I have a cheap-y black light tube I bought a few years ago, but I think it’s about reached the end of it’s useful life. Any suggestions?

 

[Garry H (Cut Nut)]

I’d appreciate recommendations for a good (but not crazy-expensive) blacklight light to test with ... like a penlight style. I have a cheap-y black light tube I bought a few years ago, but I think it’s about reached the end of it’s useful life. Any suggestions?

The cheap black light (around 400nm) will usually cause way stronger fluorescence than the 365nm that Bryan Texus WF uses. I feel GIA is now using 385nm but on older certs they would definitely have been using 365nm.
To get the positive effect of color enhancement the cheap tool is best because there is abundant of those visible and near visible radiation all around us.

@Stephan send me certs of diamonds you know to have transparency issues.

I think I am now at or close to being able to identify all diamonds with transparency issues from reports and 385nm photos which some suppliers are now using.

 

[sledge]

I think I am now at or close to being able to identify all diamonds with transparency issues from reports and 385nm photos which some suppliers are now using.

Please elaborate.

Do you need the 385nm photos with the report, or can you do it with a report only?

My own thoughts are surface graining, whisps and clouds would contribute to.tramsparency issues. No science to back it up, just a gut feel.

 

[Garry H (Cut Nut)]

Please elaborate.
Do you need the 385nm photos with the report, or can you do it with a report only?
Whitish blue is a dead give away
My own thoughts are surface graining, whisps and clouds would contribute to.tramsparency issues. No science to back it up, just a gut feel.
I think you are warm.

I am hoping someone we know might share or publish something that was presented at the Montenegro Mediterranean Gem Conference 2018 that states that there are no fluorescence transparency issues.

 

[the_mother_thing]

@Garry H (Cut Nut) I don’t know what strength the one I have is; the bulb has “BLB-T5/4W” printed on it ... that is all I know.

 

[Garry H (Cut Nut)]

@Garry H (Cut Nut) I don’t know what strength the one I have is; the bulb has “BLB-T5/4W” printed on it ... that is all I know.

Looks like a relatively short wave mercury vapour UV lamp.
possibly like this mineral lamp from page 87 https://pdfs.semanticscholar.org/fd86/426ab45369629de85ab47ac287845b3a879c.pdf

 

[Dancing Fire]

I’d appreciate recommendations for a good (but not crazy-expensive) blacklight light to test with ... like a penlight style. I have a cheap-y black light tube I bought a few years ago, but I think it’s about reached the end of it’s useful life. Any suggestions?

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[Texas Leaguer]

The cheap black light (around 400nm) will usually cause way stronger fluorescence than the 365nm that Bryan Texus WF uses. I feel GIA is now using 385nm but on older certs they would definitely have been using 365nm.

We use an official GIA cabinet for our analysis:

GIA UV Lamp and Viewing Cabinet

store.gia.edu

An interesting feature of this new version by GIA is the test strip. The fluorescent strip benchmarks strength of faint, medium, strong, and very strong. And our experience has been that it corresponds quite well to the descriptions on reports.

While GIA has physical master sets against which to assess fluoro, very few jewelers do, so this is really an excellent innovation.

 

[Texas Leaguer]

I am hoping someone we know might share or publish something that was presented at the Montenegro Mediterranean Gem Conference 2018 that states that there are no fluorescence transparency issues.

Garry,
With regard to using photos of fluorescence as aid to diagnosing transparency remotely, it will be highly unreliable as the both the strength and color observed will be greatly affected by camera settings. Here is a good illustration of the problem. Both images are of the same set of diamonds in the same UV cabinet, but taken at different exposures. Notice how 'white' the stones are with the greater aperture.

 

[Garry H (Cut Nut)]

Garry,
With regard to using photos of fluorescence as aid to diagnosing transparency remotely, it will be highly unreliable as the both the strength and color observed will be greatly affected by camera settings. Here is a good illustration of the problem. Both images are of the same set of diamonds in the same UV cabinet, but taken at different exposures. Notice how 'white' the stones are with the greater aperture.

The only system I know of is what Sergey and OctoNus developed using 385nm LED Bryan and is part of the DiBox2 system.
I trust it more then the GIA dinosaur 365nm system that I very much doubt GIA use in their own labs.