GIA undetermined D color??

Date: 6/16/2009 5:37:06 PM
Author: Wink
What the heck is an 'undetermined' D?


Wink

Date: 6/16/2009 5:36:31 PM
Author: Modified Brilliant
Aren't they the authority?

Date: 6/16/2009 5:37:06 PM
Author: Wink
What the heck is an 'undetermined' D?

Wink

Date: 6/16/2009 6:56:42 PM
Author: adamasgem
I believe it refers to the origin of the color, possibly being due to HPHT decolorization treatment...

D's and E's are difficult, in some circumstances to determine treatment, due to spoofing techniques, like post HPHT decolorization radiation and then annealing to sharpen the radiation induced GR1.


I've heard of other paper, where they basically admit, they can't tell, which is the PROPER thing to do.


Stone is probably a type IIa.

Date: 6/16/2009 7:25:15 PM
Author: Stone-cold11
So what happen to the perceived value of the stone in this case?

Date: 6/16/2009 11:18:01 PM
Author: Richard Sherwood


Good question, Stone Cold.

In the case of my client's stone, it was the kiss of death. We're talking about a very large, high quality, high dollar stone, and the GIA's 'indeterminate' designation not only cut the value in half, but killed the liquidity.

Bear in mind that we had documentation that this stone had been held in my client's family for three generations.

So what I did was thoroughly document the origin of the diamond, and its subsequent passing through the generations, and the recutting (to an Infinity super ideal cut by the way). Then I noted the GIA's certification as to color and clarity (D/VVS1), and with Paul Sleger's help obtained a 'free and clear' cert from the HRD lab in Belgium, which considered the origin and pedigree of the stone in arriving at their final designation.

My client then realized sale of the diamond on the Antwerp market. He was very happy.

It was a long and involved process, but well worth the trouble. My client realized double what he would have if he'd have if he'd rolled over and played dead after receiving the GIA report.

Date: 6/17/2009 12:42:04 AM
Author: strmrdr
Marty does anyone anywhere today have the equipment/methodology to prove beyond a reasonable doubt that such a stone is not treated if the history is not known?

Date: 6/16/2009 6:56:42 PM
Author: adamasgem

I believe it refers to the origin of the color, possibly being due to HPHT decolorization treatment...
D's and E's are difficult, in some circumstances to determine treatment, due to spoofing techniques, like post HPHT decolorization radiation and then annealing to sharpen the radiation induced GR1.

I've heard of other paper, where they basically admit, they can't tell, which is the PROPER thing to do.

Stone is probably a type IIa.

Date: 6/17/2009 2:45:14 PM
Author: DiamondFlame
Wow. I learn something new today. I've heard of color enhancements. I didn't know they can decolorize diamonds too! In this instance, how did GIA find out about the HPHT treatment prior to its grading attempt?

Date: 6/17/2009 10:45:21 AM
Author: adamasgem
Storm.. I really can't answer that question definitively, as most seem to hide their information as proprietory.


It requires cooperation between the mine producers and the reseachers, so far, something that is sorely lacking, due to apparent conflicting interests. When asked for a guaranteed untreated D as a pure reference for our research there were lame excuses why they couldn't supply same, nor did DeBeers, to my knowledge, attempt to duplicate the results we obtained with 218nm excitation.


Ambiguity seems to be in the better interests of the producers, and the trade probably wouldn't pay the actual costs involved in testing such stones, as it takes just a much time to test for HPHT treatment, on a 1/4 carat as a 10 carat, let alone the high cost of the equipment.


In my opinion, ALL paper should indicate whether a stone could potentially have been be decolorized (IIa/IaB), a screening test that is relatively easy. Actual typing IIa vs IaB requries FTIR equipment (maybe 30K to 40K $) and some Raman units with enough sensitivity goes for the six figure category, if you want to look at ALL the quazi definitive criteria, now in practice.


Interestingly, there is a GE patent, developed at the same time that it was being said to the trade and public that HPHT was undetectable, that talked to detection using a TWENTY watt laser, not the 50 to 100 MILLI WATT lasers in use in Raman/PL units. I still think that the experiments performed at AGS with the DiamondView excitation, should be further investigated.


We once almost got our hands on a carat sized IIa stone, with indented trigons ,as a potentially representative and plausably untreated D reference, but that fell through for various reasons.