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»  » AGTA vs GIA testing capabilities and limitations
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AGTA vs GIA testing capabilities and limitations |
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| P: 7/31/2004 10:14:46 AM | |
puzzled Rough Rock Total Posts: 1 Last Post: 7/31/2004 Member Since: 7/31/2004 |
I recently ran into serious dilemma. According to AGTA identification lab they can determine in 100% of cases for all blue sapphires whether they were heat treated and/or diffused with beryllium or other elements. According to AGTA they would need only further testing for beryllium or other elements for other color stones (like, yellow, orange, pink, etc) and they are absolutely 100% positive to provide that determination for any blue sapphire. Imagine my disbelief when I was stunned with GIA representative statement who said that they could not guarantee anything, even for the blue sapphires. I was under the impression that both labs are equally equipped and qualified for the task. Are my assumptions wrong? Can anybody enlighten me what is going on here? Does lattice diffusion or any other diffusion for that matter require high temperature heating? I was under the impression that it is a prerequisite. Also, how blue sapphire can be treated with other methods except high/low heat?? If it can be, what would be the element and color of original stone?? Somebody told me that they can take very dark blue stone and turn it into medium color blue. Is it true? BTW, for the sake of this discussion, let's assume that stone is from Sri Lanka. HELP!!!! |
| Posted: 7/31/2004 10:14:46 AM | |
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There are 5 replies to this message. There are 5 replies on this page. |
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| P: 8/4/2004 6:22:52 AM | |
Vincent Pardieu Cut Rock Total Posts: 408 Last Post: 3/7/2008 Member Since: 1/21/2004 |
Well, That's a lot of questions and that a post which is not that simple to answer. I will try whatever... Your first question was about GIA and AGTL equipment: To my knowledge they have both access to many useful instruments, but now for political reasons they advertise or they dont advertise on their capacities to do this or that. I dont know them more than that so I will let other to try to help you here. On your question if beryllium treatment require high temperature, my answer is (to my knowledge) definitively: Yes! and even i think many companies doing that are also using some kind of pressurisation (which means pressure but not at a level similar to HPHT) But now 2 years ago I've heard in bangkok of some russian scientists seaching some money which told several people that he was able to make a colorless sapphire pink without heat... I thought it was fist a joke... but well... may be not. There is a possibility of "ionic implantation" that was suggested by some friends of mine in France and which is already in the market for topaz from the leslie and co company: www.leslieandco.com These friends told me that the ionic implantation technology does not require heat and can be adpated to emeralds and corundum... It means that technically we can add without high temperature some ions (chromium, Iron, Beryllium,...) to a gemstone without to heat it (except may be locally) and so without to modify its inclusions. Well now I'm searching to get see some specimen or get more informations in order to see more clearly about these possibilities... But I cannot be sure of anything. I was told without to be able to verify the information that some tests had been performed already in europe and the US and that such a machine has been bought by a company (unknown to me) in Thailand... So in theory yes its probable that in the coming years we will see some low temperature diffusion process in most gemstones... may be they are already in the market? I dont know about that... May be you get the same kind of information as me. May be not... But in this case we have to be very careful as none of these informations are verified. But it is clear to my mind that with the technological evolution we will see more and more treatments in the coming years! So why not that? In thisspecific case I think that probably to activate the diffused ions some heat treatment under reducing or oxydising atmosphere is probably required. To my knowledge blue sapphire comes from Iron and titanium or from iron alone... diffused of initialy present inside the gem. About the very dark blue sapphire, the heat treatment technology using beryllium additive can lower the blue saturation of a given gem as it is eliminating the purplish or the greenish part of sapphire by removing the blue... The result are bright orange and yellow gems. So if applied to dark blue sapphire, yes probably the stone can be less blue. I've already seen in Bangkok some blue sapphire heated with beryllium. They were fine medium tone blue sapphires but I did not see these stone before heat treatment. Whatever this domain is very difficult and opaque. To see clearly in this area a lot of money for research is required and information and cooperation from burners, dealers and laboratories is needed. As currently they dont agree with each other so this area will probably stay a grey and opaque area for a while... Some people greed associated with the ignorance of others make the gem business a very dynamic domain! All the best, Vincent Pardieu, "travel addicted gemologist". |
| Posted: 8/4/2004 6:22:52 AM | |
| P: 8/4/2004 7:49:47 AM | |
Cave Keeper Cut Rock Total Posts: 264 Last Post: 9/23/2005 Member Since: 6/30/2004 |
That's why I've lost total interest in diamonds, rubies, sapphires, emeralds and imperial jadeite. Soon, it may be others ... Thunder Storm Maker (Grand Master), creating havoc in the Heavens when active. Otherwise just a lazy Cave Keeper, sleeping on a huge pile of tiny glittery rocks, small dazzling stones and big sparkling pebbles. |
| Posted: 8/4/2004 7:49:47 AM | |
| P: 8/4/2004 8:20:07 AM | |
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Vincent Pardieu Cut Rock Total Posts: 408 Last Post: 3/7/2008 Member Since: 1/21/2004 |
---------------- It is very sad if its true as there are many ways to detect these treatments... You know when the first flame fusion synthetic rubies were created by Verneuil at the end of the XIX centuries... Many people have think that ruby was not safe anymore, thus the reason why some companies have chosen diamonds as their main object of promotion... But soon the microscope began to be used by gemologists and flame fusion stones were easy to differenciate from natural ones. because of this inclusions were seen not anymore as just flaws or bad things but as some valuable tale tell things if they do not lower the general beauty of the stone... New synthethics or new treatments means only that new lab instruments or gemological techniques will appear. I'm not that affraid... All the best, Vincent Pardieu, "travel addicted gemologist". |
| Posted: 8/4/2004 8:20:07 AM | |
| P: 8/7/2004 2:01:47 PM | |
norman_in_L.A. Rough Rock Total Posts: 40 Last Post: 11/13/2009 Member Since: 7/26/2004 |
Puzzled:
Even with all the tools & the most up to date equipment at GIA & at AGTA sometimes the answer to the question "Has this sapphire been treated in some way?" is we cannot tell, or unknown. The GIA rep gave you the right answer. Treatments are constantly being changed and updated. The equipment that the cooker uses, the process he uses, the temperature he uses, the chemicals that he uses. There is no way on this earth that GIA or AGTA, or for that matter the Gemologist on the street can stay ahead of the colored stone cookers. We can only hope to stay one step behind them.
Both GIA & AGTA are members of mutually benifiting organizations and committee's such as the LMHC (Laboratory Manual Harmonization Committee). The LMHC just put out a paper on Standardised Gemmological Report Wording. Speaking of reports I recently read a paper on low temerature lattice difusion ( I'll post it next week) beign used by a cooker in of all places Sri Lanka.
I was in Thailand this past February, I can attest to the fact that the colored stone cookers are using new technology. The days of heating sapphire at the bottom of an old 50 gallon barrel are gone. I can tell you it is very satisfying to tell a customer the answer to the question that his or her sapphire is treated or not, but sometimes we say "No, we can't tell".
Norman
Norman Monteau |
| Posted: 8/7/2004 2:01:47 PM | |
| P: 8/17/2004 12:03:15 AM | |
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yowahking Cut Rock Total Posts: 317 Last Post: 11/13/2004 Member Since: 8/16/2004 |
One of the best experts in this area is an appraiser in Colorado Springs, CO. He is also the head of education for Jewelers of America. He was an instructor at GIA and speaks in the US and in Thailand at GIA there. Most people don't know that the old heat treatment actually diffused Hydrogen into the gems which happened by accident for a hundred years. Treatments will find a niche in the market, it is jewelers who put their head in the sand and pretend it will go away. Some stones like Aqua are the same price whether heated or not. Some sapphires will require a disclaimer that the treatments are so new that they may not be detected at the time of viewing and should be looked at again in 2 years. Appraisers will love that one, jewelers will hate it. Customers will still buy what they think is pretty and decide whether the value equals the "feeling" they get from it like art. Scott
Scott Bohall |
| Posted: 8/17/2004 12:03:15 AM | |
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