Expert question for gemologists??

[oldminer]

I have a dealer customer who wants us to authenticate about 100 P/Q/R color diamonds as natural origin of color.

What would your basic tests for this be? What would be your secondary tests or do you think simple testing for diamond type 1a would be adequate to screen these sufficiently.

Type 1a are colorless to cape series stones.
Type 1b contain the "fancy yellows"
Type 2a are the brown series, the synthetics and a few rare naturals other colors (about 1%)
Type 2b are the natural and sythetic blue stones (with boron) that are electrically conductive. The synthetics are generally also magnetic.

I know HTHP can be used on any stone, but I don''t think type 1a diamonds would be worked on to obtain P/Q/R colors. It would sort of be a wasted effort.

Any assistance in this would be greatly appreciated.

Thanks.

 

[Garry H (Cut Nut)]

Jim Shigley showed an example of a 1Aa brownish yellow HPHT treated stone at the HK show.

I had 6 stones treated and one mid champagne color came back as about M-N color, but it was near type II (I only sent stones that allowed a little UV transmission).

PQR yellowish is worth more than light brown / champagne

 

[oldminer]

Garry;

The subject is seemingly complex. Are you implying that someone might HTHP some brownish type II stones to get P/Q/R color cape colors for financial reasons? Do you think that if the diamonds are yellow, not brownish or brownish yellow, and test as 1a, that one might assume they are not HTHP?

I am looking for a rapid and inexpensive screening process, with a decent degree of assurance, based on mass processing many (100) stones rather than strictly authenticating a single diamond with total security. Most labs need a feeling of total security on each diamond. The sort of situation I am involved in gains accuracy by the number in the sample preventing the single unusual conclusion to be mistaken by doing a simple procedure for many stones of similar type.

I think being sure the diamonds are type 1a makes us pretty sure, for a related group of stones, that there is no large chance of HTHP. Would you agree?

 

[Garry H (Cut Nut)]

I think De beers Diamondsure is the first terst Dave.
IGI and EGL USA do it on all stones I believe.

After that - hmmm - I think I would send one of the nicest looking stones to a big lab.

 

[denverappraiser]

Dave,

I vaguely recall that 1a stones have a different xray transparency and you might be able to use this. I have a veterinarian that I use to xray pearls from time to time who is happy to work for a pretty reasonable fee. Perhaps even free because it’s such an interesting project. GIA should be able to tell you if there would be anything diagnostic from such a test. Let me know what you learn, I always duck requests for color origin determination testing but I would love to learn a reasonable approach.

Neil Beaty
GG(GIA) ISA NAJA
Independent Appraisals in Denver

 

[oldminer]

The DiaSure tests mostly for synthetic diamonds if I am not mistaken. I believe it is testing for short wave UV opacity/transparency. This is a type I versus a type II separation test, I believe. Anyone know if this is correct? Synthetics are type II (most all the time) and natural diamonds are type I, app 99% of the time......

I can rapidly screen for UV opacity, transparency without that expensive device. If that is the tool and it does what I think it is doing, then I can feel pretty confident in the simple screening I have in mind.

 

[denverappraiser]

The deBeers device tests for UV opacity. Their ads claim that it tests for IIb and is useful for detecting synthetics. There are, of course, far less expensive ways to test for this if it suits your requirements but I don''t think it is going to answer the HPHT question that you are asking. SSEF makes a competitive tool for this. Perhaps they could give you some clues.

Neil Beaty
GG(GIA) ISA NAJA
Independent Appraisals in Denver

 

[Paul-Antwerp]

I would work with probabilities, although scientifically, this might not be defendable.

If most of the stones are of smaller size, let us say under 1.50 Cts, I would not suspect HPHT-treatment on them, since it is hardly worth the trouble and the cost, ending up with a low colour.

I would put the rounds on the side, and concentrate further on the fancy shapes (most stones suitable for HPHT are not round). When checking the fancy shapes, I would try to find remainders of the burnt surface after the HPHT-treatment, especially in the ones just above a magic size. Normally, a cutter will take care to polish out the burnt surface, but at the edge of a magic size, there is a high chance of him ''missing'' a spot, and leaving a burnt surface, especially around the girdle area.

If all this proves negative, combined with your test for Ia, I would trust the result.

Live long,

 

[Richard Sherwood]

I've seen some 1a HPHT treated stones which were only cape or dark cape in color. They were a carat plus and under in size, and had been treated in China. Most had a subtle hint of brown or green to them.

I don't know that I would use only the 1a criteria for a conclusive identification. Out of a 100 stones though, at least some should show some "frosting" (as Paul indicates) or graphitization, if it were an HPHT parcel. If you don't see any indication of that, and the yellow color is relatively pure, and you send out possibly 1 to 3 stones out for analysis with advanced instrumentation, then it might be a comfortable enough situation to sign your name to.

Taking a devil's advocate position strictly on a hypothetical and cautionary basis- If I were inclined in the direction of deviousness, and had a parcel of HPHT stones which I wanted to legitimize with documentation, I would avoid a major lab with known HPHT detection equipment and instead hope to slip them past a well known independent lab.

 

[RockDoc]

HPHT

First, David, I am of the opinion that, HPHT testing detection hasn''t reached it''s totally conclusive level.

There are several ways to sort out the easy ones from the not so easy ones. BUt I don''t think any of them are totally conclusive, unless there is conclusive evidence which doesn''t support an abbreviated testing procedure.

I would suggest the following...

If you have it take note of the updated AGS client contract. They do a pretty good job of stating their liability for this type of testing. Reviewing their example of disclosing the terms and conditions, is probably a good lead for all the labs.

I have the agreement with your client ( David Atlas''s client) agree to a specific set of terms and conditions, that you feel ( or your attorney feels would CYA from future liability, should future improvements in the testing occur.

Then I would quote maybe one level of pricing for those stones that can be "safely" eliminated as not being treated. This could be based on Diamond Sure, SAS 200, SSEF, HRD or other equipment ( with a statement of your reliance on the results of that equipment in the agreement).

And I''d have another price level that provides the client with the option of further testing at an additional cost that you feel comfortable with ( either a flat rate, or stone by stone charged based on the amount of testing needed to base a conclusionary report on.

However, there is evidence that HPHT many times will cause extreme strain to develop in HPHT treated stones. I am not sure of the level of postive conclusiveness of this, but for stones that have significant strain, it is sort of a "warning" light indicating more attention and testing. This would possibly assist your desire to make an abbreviated testing procedure, although from a legal liability issue, how this would impact the assignment.

It is sort of obvious that your client wants to use your reports to third parties. I''d be really cautious in the consideration of this factor.

I''d appreciate hearing yours and other expert''s opinions of the above.


Rockdoc

 

[oldminer]

I think we can all see the depth and complexity of this "problem". In spite of the fact that I am now faced with the "problem", it is truly much larger than a personal situation. We are all left in a pickle about what to do, not do, what to sign, not sign and on and on. Little conclusive results are given with simple testing and our business is certainly populated by a few devious individuals although the vast majority are not bad people at all.

I have some answers now. Better than before, at least. I am going to do the work and try to be careful. It is a fine line to walk between making a living and destroying one''s reputation. Life is a challenge.

 

[Rhino]

Someone correct me if I''m wrong but isn''t a spectroscope the tool for this job? If I remember correctly naturally colored diamonds have a different absorption spectrum than color treated stones.

 

[Garry H (Cut Nut)]

Yes Rhino, but I think Dave has mentioned before he can not justify the expense.

Dave here is your answer - send tem of to Marty Haske for an opinion.

 

[oldminer]

I do have the Haske spectrophotometer in my office. I think it can differentiate the diamond types, to an extent, in its present configuration, but I do not have the upgrades to see the non-visual light wave spectra. I think it needs a $30K+ upgrade for that. It is not worth it for 100 stones..... Theere is a limit on what I can charge for the work, if I can agree to even do it.

 

[Richard Sherwood]

Date: 4/13/2005 12:42:21 AM
Author: Rhino
Someone correct me if I''m wrong but isn''t a spectroscope the tool for this job? If I remember correctly naturally colored diamonds have a different absorption spectrum than color treated stones.

Advanced spectroscopy is the key to detecting HPHT enhancement. While HPHT synthetic diamonds can usually be identified with traditional equipment by a gemologist trained in what to look for, HPHT enhancement of natural diamonds is much more difficult to determine. Traditional spectroscopic equipment and technique is not sensitive enough to pick it up.

Marty Haske uses a combination of his SAS-2000 spectrophotometer along with a liquid nitrogen setup to cool down the diamond and a Raman laser system to study the photoluminscent spectra. This spectroscopic setup and technique is capable of conclusively identifying the vast majority of HPHT enhanced diamonds.

The SAS basic unit runs about 20 grand, with the most applicable set of Raman lasers running an additional 12 grand. There''s several other sets of specialized Raman lasers which work better for one purpose or another, each costing about 12 grand.

 

[Richard Sherwood]

Date: 4/12/2005 4:43

1 PM
Author: RockDoc

However, there is evidence that HPHT many times will cause extreme strain to develop in HPHT treated stones. I am not sure of the level of postive conclusiveness of this, but for stones that have significant strain, it is sort of a 'warning' light indicating more attention and testing.

The strain aspect is an interesting sidebar regarding HPHT diamond analysis. I've only read about it in regards to the brown stones being enhanced to whiter body colors, in which case the annealing process of HPHT tends to relieve strain rather than creating it or accentuating it.

Have you seen information which indicates it is the reverse for stones treated to bring out fancy colors?

 

[RockDoc]

Date: 4/13/2005 9:58:10 AM
Author: Richard Sherwood

Date: 4/12/2005 4:43

1 PM
Author: RockDoc

However, there is evidence that HPHT many times will cause extreme strain to develop in HPHT treated stones. I am not sure of the level of postive conclusiveness of this, but for stones that have significant strain, it is sort of a ''warning'' light indicating more attention and testing.

The strain aspect is an interesting sidebar regarding HPHT diamond analysis. I''ve only read about it in regards to the brown stones being enhanced to whiter body colors, in which case the annealing process of HPHT tends to relieve strain rather than creating it or accentuating it.

Have you seen information which indicates it is the reverse for stones treated to bring out fancy colors?

Hi Richard....

All of this stuff is pretty new, and is subject to change in the future.

I was told by someone very knowledgeable that one of the pre-bases operations of HPHT of natural brownish stones or yellowish rough is to treat the rough and then saw it if there is variance in the color, where the HPHT doesn''t result in a uniform change, and that the part of the rough which might be "darker" is then sawn from the other section of the diamond, and possibly is re-treated to acheive a more colorless piece, and the more colored piece cut to enhance the color, and attempt to sell as a fancy color.

All of this stuff is reletively new, and personally, I''d shy away from analyzing the treatment or natural color of such stones.

This is pretty intense work, and I dont think the trade wants to compensate labs to do this stuff. There is, as you''ve said a huge financial committment on the part of the lab, and if conclusive testing results are required, people who want these tests done, are going to have to compensate the labs for this extra work.

The future of any legal liability is almost more of a consideration to be made than the decision to invest in all the equipment necessary to discover treatment.

It is sort of my opinion that if one wants to be involved in doing this work you have to make a significant investment, to be sure that the results are really dependable for the client and any other forseeable third parties.

I really don''t think there''s a way to do this, for some "troublesome" stones and how much of the HPHT information do we really have?

I certainly agree with your position of those who want to bypass the major labs to the smaller more independent ones, and perhaps its better to turn down such assignments so it doesn''t turn into a future nightmare, as more equipment updates any procedures for detection in the future.

I would rather do well, what I know to be "safe" to do, until such time that there really is more knowledge about this stuff.

The strain situation and consideration is only indictitive rather than conclusive, but its certainly a way to pick out suspect stones, with the equipment we currently have without making an investment, in very pricey equipment which may become obsolete in the future.

Rockdoc