shape
carat
color
clarity

Fraudulent temporary diamond coating to improve color

kenny

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
32,188
Wow, it's amazing what the crooks will do! :knockout:
 

Tekate

Ideal_Rock
Premium
Joined
May 11, 2013
Messages
7,561
This is serious. Sad to read. Jail for all.
 

WinkHPD

Ideal_Rock
Trade
Joined
May 3, 2001
Messages
7,516
Thank you Garry.

This was an interesting, and disturbing thing to read on a Sunday morning.

Kudos to the lab for not only catching the problem, but for intelligently deciding how to have it officially recognized.

It is going to get interesting as the repercussions spread like ripples in a pond.

Wink
 

ariel144

Ideal_Rock
Joined
Jan 21, 2006
Messages
2,014
Saw that...don't know how they think they can get away with it and not get caught.
 

VRBeauty

Super_Ideal_Rock
Premium
Joined
Apr 2, 2006
Messages
10,992
Garry - this story is fascinating, especially to one who loves mysteries and analytical processes. Thanks for posting it!

It sounds as if in this case, the fact that the same stone had been certified not long before the treated stone, and someone recognized the stone (helped in part no doubt by its substantial size) prompted IGI to have witnesses on hand for the stone's second analysis. But - if I read the story correctly, the IGI would likely have identified a problem had they not recognized the stone, because there would have been a discrepancy between the color "read" by the colorimeter and that observed by the IGI's human grader.

Do all of the major labs use a colorimeter as part of their grading/certification process? Is this true irrespective of the size of the stone?
If so, how did those 400 or so GIA-graded stones whose certificates were recalled as part of this investigation initially slip through with incorrect certs?

Do independent appraisers generally use a colorimeter?

Someone - I think it was Kenny - previously alerted us to part about the 400 GIA recalled certs. It's nice to have this additional background about how the IGI discovery unfolded. What's not clear is what this changes for us consumers.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
17,903
VRBeauty|1434907200|3892231 said:
Garry - this story is fascinating, especially to one who loves mysteries and analytical processes. Thanks for posting it!

It sounds as if in this case, the fact that the same stone had been certified not long before the treated stone, and someone recognized the stone (helped in part no doubt by its substantial size) prompted IGI to have witnesses on hand for the stone's second analysis. But - if I read the story correctly, the IGI would likely have identified a problem had they not recognized the stone, because there would have been a discrepancy between the color "read" by the colorimeter and that observed by the IGI's human grader.

Do all of the major labs use a colorimeter as part of their grading/certification process? Is this true irrespective of the size of the stone?
If so, how did those 400 or so GIA-graded stones whose certificates were recalled as part of this investigation initially slip through with incorrect certs?

Do independent appraisers generally use a colorimeter?

Someone - I think it was Kenny - previously alerted us to part about the 400 GIA recalled certs. It's nice to have this additional background about how the IGI discovery unfolded. What's not clear is what this changes for us consumers.

High VR, The Colorimeter device IGI quoted as being used is an older machine - that company has long ago been taken over by Sarine - and I am not sure they managed to imporove on the earlier Gran model. GIA use their own inhouse developed colorimeter as the basis of their color grading, and only override the device when two or more humans disagree with it. So I do not know if their device also gives the real grade - but we should expect that it does not, or worse still - that they even stopped human checking????
 

Paul-Antwerp

Ideal_Rock
Trade
Joined
Sep 2, 2002
Messages
2,859
I think you are mistaken, Garry, about the colorimeter IGI quoted.

In the analysis of these stones, they used the Zvi Yehuda colorimeter, a device used to estimate body-color of rough diamonds, not at all the Gran Colorimeter for polished that you are referring to.

Live long,
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
17,903
Paul-Antwerp|1434967588|3892543 said:
I think you are mistaken, Garry, about the colorimeter IGI quoted.

In the analysis of these stones, they used the Zvi Yehuda colorimeter, a device used to estimate body-color of rough diamonds, not at all the Gran Colorimeter for polished that you are referring to.

Live long,
Thanks Paul. Yes - and i think it is primarily for rough diamond color grading?
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
17,903
Paul-Antwerp|1434967588|3892543 said:
I think you are mistaken, Garry, about the colorimeter IGI quoted.

In the analysis of these stones, they used the Zvi Yehuda colorimeter, a device used to estimate body-color of rough diamonds, not at all the Gran Colorimeter for polished that you are referring to.

Live long,
Thanks Paul. Yes - and i think it is primarily for rough diamond color grading?
 

Paul-Antwerp

Ideal_Rock
Trade
Joined
Sep 2, 2002
Messages
2,859
No worries, Garry.

Your extra question takes us off-topic, but I will gladly clarify.

I would not call it rough diamond 'grading', rather predicting or estimating. It is a tool used by most buyers of rough diamonds nowadays to assist them in their purchasing of rough. As the sellers of rough are also using it, it is kind of necessary for a buyer to use it too in order to be on a level playing field.

Using the tool however takes experience. One cannot simply use the resulting estimation and rely on it. One needs to understand that the estimate the tool gives is dependent upon aspects like fluorescence and origins of the rough, just to name a few. A buyer of rough diamonds thus needs to combine the machine's result with his experience to arrive at a personal estimation of the final color. Not at all foolproof, I would say.

As every polished diamond in essence also is a rough diamond to be improved to a better polished diamond, the machine can also be used on polished diamonds, but it is not common practice. That IGI apparently used it in this analysis is remarkable, counter-intuitive even.

Live long,
 
Be a part of the community Get 3 HCA Results
    Ultimate Valentine's Jewelry Gift Guide
    Ultimate Valentine's Jewelry Gift Guide - 02/05
    Valentine's Date Night Jewelry
    Valentine's Date Night Jewelry - 02/03
    Did You See January 2023's Jewels Of The Weeks?
    Did You See January 2023's Jewels Of The Weeks? - 01/28
Top