Can GIA make mistake???

[chrono]

Yes, my diamonds with no fluoro can also look a touch bluer when outdoors due to it reflecting the blue sky.

 

[Garry H (Cut Nut)]

What you are seeing is the effect of a totally different UV frequency or wavelength from your sources compared to what GIA and gemologists use.
Like so many things about our ancient and antiquated industry, we use tools that were available, not ones we should.

I have mentioned this before and some of the people who have replied seem to have overlooked what seems to be your an explanation too.
This article is heavy going for many, but if you just look at the charts on Figure 4. Note that the UV Loupe light emission of 403A is further to the right - infact it is at the edge of the violet visible range (395-450A).
http://www.gia.edu/gems-gemology/summer-2013-luo-fluorescence-optical-defects
This explains why your diamond is fluorescing with the readily available torch as opposed to the long wave used by labs.
So your stone is probably fluorescing nicely in all sorts of light and making the color less yellow.
Enjoy it

 

[uixs]

Wow...It was really interesting to read the article.
It make sense why my stone was fluorescing...
Thank you for your input

 

[Texas Leaguer]

What you are seeing is the effect of a totally different UV frequency or wavelength from your sources compared to what GIA and gemologists use.
Like so many things about our ancient and antiquated industry, we use tools that were available, not ones we should.

I have mentioned this before and some of the people who have replied seem to have overlooked what seems to be your an explanation too.
This article is heavy going for many, but if you just look at the charts on Figure 4. Note that the UV Loupe light emission of 403A is further to the right - infact it is at the edge of the violet visible range (395-450A).
http://www.gia.edu/gems-gemology/summer-2013-luo-fluorescence-optical-defects
This explains why your diamond is fluorescing with the readily available torch as opposed to the long wave used by labs.
So your stone is probably fluorescing nicely in all sorts of light and making the color less yellow.
Enjoy it

Garry, thanks for the link to the article. Indeed it is heavy going for the non-physicists in the crowd, myself being one! The particular relevance this article has for this thread, and which you alluded to, is the great variability in the wavelengths that the various UV light sources produce- even those used commonly in the trade and in the labs.

For instance, this statement is made in explaining the difference between two of the UV light sources studied:
“Extra” emission from the conventional UV lamp at 405 nm causes the diamond’s blue fluorescence to be more intense than that from a “pure” 365 nm LED source. Such discrepancies contribute to problems with consistency and reproducibility of fluorescence observations within the industry.

If you consider the full range of UV light sources available out there for a whole variety of uses (such as nail drying in this case), there is no telling which wavelengths they are actually outputting. If a particular blue fluoro stone with a specific color center is stimulated at a particular wavelength and the UV source is low in that wavelength then fluoro will not be stimulated or will be stimulated very weakly. Conversely, if the source is for example putting out some visible violet (around 415 nm), the diamond may show some fluorescence where none would be present under a strictly contained UV source such as might be used in the lab. That could in fact account for this discrepancy between what we see in the photos and the GIA report.

As for the notion that the stone is "probably flourescing nicely in all sorts of light and making the color less yellow", I do not see anything in this study to support that. In fact, the modern science seems to be rather clear in terms of the intensities of UV and VV that are required to activate the fluorescent effect. Because UV intensity drops off so dramatically with distance from articicial light sources, normal indoor lighting environments (even overhead fluorescent tube lighting) are essentially UV free.

This particular article mentions that fact but does not specifically discuss it:
Observation of fluorescence can be affected by three main factors: (1) the nature of the emission from the UV light source; (2) the nature of the defect(s) responsible for the fluorescence; and (3) methodology, including the viewing geometry and the distance from the radiation source.

Other studies do demonstrate that diamonds must be observed within inches of indoor light containing a UV component in order to activate fluorescence and any color masking that might accompany it.

 

[Rockdiamond]

You're beating a very dead horse Bryan.
You are basing your argument on articles that don't even dispute the facts- instead of actually observing a simple to see physical characteristic.

Certain SB or MB stones in the D-L color rage look whiter than their body color in normal room lighting.
Please look at some actual diamonds so you can see for yourself.

 

[Texas Leaguer]

You're beating a very dead horse Bryan.
You are basing your argument on articles that don't even dispute the facts- instead of actually observing a simple to see physical characteristic.

Certain SB or MB stones in the D-L color rage look whiter than their body color in normal room lighting.
Please look at some actual diamonds so you can see for yourself.

My horse is very much alive David. I look at diamonds every day and I read the science. But thank you for the kind advice just the same.

 

[Garry H (Cut Nut)]

What you are seeing is the effect of a totally different UV frequency or wavelength from your sources compared to what GIA and gemologists use.
Like so many things about our ancient and antiquated industry, we use tools that were available, not ones we should.

I have mentioned this before and some of the people who have replied seem to have overlooked what seems to be your an explanation too.
This article is heavy going for many, but if you just look at the charts on Figure 4. Note that the UV Loupe light emission of 403A is further to the right - infact it is at the edge of the violet visible range (395-450A).
http://www.gia.edu/gems-gemology/summer-2013-luo-fluorescence-optical-defects
This explains why your diamond is fluorescing with the readily available torch as opposed to the long wave used by labs.
So your stone is probably fluorescing nicely in all sorts of light and making the color less yellow.
Enjoy it

Garry, thanks for the link to the article. Indeed it is heavy going for the non-physicists in the crowd, myself being one! The particular relevance this article has for this thread, and which you alluded to, is the great variability in the wavelengths that the various UV light sources produce- even those used commonly in the trade and in the labs.

For instance, this statement is made in explaining the difference between two of the UV light sources studied:
“Extra” emission from the conventional UV lamp at 405 nm causes the diamond’s blue fluorescence to be more intense than that from a “pure” 365 nm LED source. Such discrepancies contribute to problems with consistency and reproducibility of fluorescence observations within the industry.
Hi Bryan,
I only got half way thru your reply - and have a meeting - but google images of lighting specrta - wyou will see there is a lot of violet higher energy light from fluoro and LED's.
e.g. this one - and in our show room we easily see a benefit from uv even though the day-light has come through glass that will knock out the higher energy much shorter wave UV like the labs use.

If you consider the full range of UV light sources available out there for a whole variety of uses (such as nail drying in this case), there is no telling which wavelengths they are actually outputting. If a particular blue fluoro stone with a specific color center is stimulated at a particular wavelength and the UV source is low in that wavelength then fluoro will not be stimulated or will be stimulated very weakly. Conversely, if the source is for example putting out some visible violet (around 415 nm), the diamond may show some fluorescence where none would be present under a strictly contained UV source such as might be used in the lab. That could in fact account for this discrepancy between what we see in the photos and the GIA report.

As for the notion that the stone is "probably flourescing nicely in all sorts of light and making the color less yellow", I do not see anything in this study to support that. In fact, the modern science seems to be rather clear in terms of the intensities of UV and VV that are required to activate the fluorescent effect. Because UV intensity drops off so dramatically with distance from articicial light sources, normal indoor lighting environments (even overhead fluorescent tube lighting) are essentially UV free.

This particular article mentions that fact but does not specifically discuss it:
Observation of fluorescence can be affected by three main factors: (1) the nature of the emission from the UV light source; (2) the nature of the defect(s) responsible for the fluorescence; and (3) methodology, including the viewing geometry and the distance from the radiation source.

Other studies do demonstrate that diamonds must be observed within inches of indoor light containing a UV component in order to activate fluorescence and any color masking that might accompany it.

 

[Garry H (Cut Nut)]

Hi Bryan,
Busy day
Note the normal LED's actually have a fair bit of light way down in the shorter wavelengths too.

 

[Texas Leaguer]

Hi Bryan,
Busy day
Note the normal LED's actually have a fair bit of light way down in the shorter wavelengths too.

Hi Garry,
The fact that various indoor light sources contain a UV component (and VV which is capable of stimulating fluoro) is not in question. The issue is whether those wavelenths are present in high enough intensity to activate fluoro and cause color masking.

Note in the graphs you posted that the intensity of the short wavelengths drops into the low end of energy. This seems consistent with the findings that the diamond would have to be very close to the source (within inches) in order for the fluoro to be stimulated.
The spike on the LED graph appears to be beyond the range in visible spectrum that is capable of causing fluoro. Do you happen to know what the specific number is? Halogen light also has a VV component I believe.

But again, distance from radiation source is key in terms of whether an artificial light source is capable of causing color masking. The GIA study you referenced also stated this fact.

 

[Karl_K]

This is an interesting thread.
A while back a friend's wife's diamond was showing signs of fluorescence in sunlight despite the GIA grade being none.
Under the GIA branded UV lamp it showed none that was detectable to the eye.
So we tested it under a bunch of automotive leak detectors at her husbands work which are UV lights of different wavelengths and under some of them there was none but others it glowed a bright blue that could not be attributed to the lights leaking visible light.

 

[Proph3tron]

I realize this is an older thread but I thought I might offer some insight into the question of GIA certification accuracy... especially for others who might stumble upon this thread.

Yesterday I purchased a GIA certified diamond from a reputable diamond merchant in Sydney Australia . It's presently 2021 but the year of grading on this diamond is 2007. The diamond is a half carat (0.500ct) Emerald cut E grade diamond that is certified as having NO fluorescence. The serial number etched on the girdle of the diamond (which is incredibly small) matches the same GIA number on the supplied certificate - which also matches the same corresponding number on the GIA website for additional verification. So I'm dealing with a stone that we can be certain has not been substituted, nor the wrong certification paired with the stone.

Normally, I'd bring a 365nm UV light (with a Woods Filter fitted to prevent any purple light from affecting the scene) with me when buying gemstones of any type. But since I knew I was buying a GIA certified diamond, I didn't see a need to bring it with me for testing yesterday. Why would anyone doubt a GIA certification? When I returned home I tested the diamond and sure enough, it's quite strong on the fluorescence level. At least in the "strong-to-very strong" category. I was more than surprised by this error.

With diamonds that range from F to say J, blue or white fluorescence can be desirable and may even push up the price - because it will cause the stone to glow slightly in UV light from the sun and this can make a diamond appear whiter than it naturally is. I think that nearly a third of all natural diamonds fluoresce as well, which is a significant portion. Personally, I don't mind fluorescence in diamonds because it can help you find or identify an item if lost or even stolen.

But during the grading process, when Diamonds that are in the D-E (colorless) range are graded, fluorescence is considered to be a "flaw" which then affects the price of the diamond. So I'm wondering just how much more I may have paid for the diamond I just bought. GIA of course don't accept any liability and appear to claim their service should be used as a guide rather than a definite declaration. On the other hand, this is their mantra: (QUOTE): "GIA is the world’s most trusted name in diamond grading and gem identification. With objectivity and expertise as its hallmarks, GIA ensures the integrity and accuracy of every report it issues."

It would seem that GIA do get it wrong from time to time. Which should be cause for concern as they claim to be world's trusted source for grading diamonds. I also note that more than a few local diamond dealers check their stock for grading errors when they arrive and I was told that if a diamond does not meet the expectations of their customers, then the customer who have have bought the stone via an online purchase will be refunded if unsatisfied or if the merchant rejects the stone. This implies that numerous errors in grading may have occured previously. Again, I find this to be a cause for concern. See attached images showing fluorescent (no long-exposures used, just handheld).