Just when you thought gem treaters were beginning to understand the importance of disclosure, a few beautiful and interesting blue sapphires have surfaced in the trade, this time from Sri Lanka … but the identification of these gems might not be so pretty.
According to a statement released by the American Gem Trade Association (AGTA), “During recent months, we at the AGTA Gemological Testing Center have observed that some blue sapphires reaching the U.S. market show indications that they are being treated by a new technique. Most of the gemstones observed range in size from 2 to 17 cts. Since these gemstones appear to be coming from Sri Lanka, the AGTA and Sri Lanka dealers and associations are working willingly and cooperatively together to determine the exact nature of the treatment.”
These large, treated blue sapphires are challenging the capabilities of the professional laboratories, and should have the Sri Lankans very worried, since they’ve been trying to keep their sapphire market isolated from the non-disclosure problems plaguing the beryllium-treated Thai sapphire industry. These new discoveries from Sri Lanka—which also imports sapphires from Madagascar—undoubtedly will cause some major concerns for the entire blue sapphire industry.
Ever since the introduction of beryllium-treated sapphire from Thailand in late 2001/early 2002, the laboratories have been very cautiously reporting about how the treatment can affect blue sapphire. The blue sapphire market is a huge industry, and any inference that the labs would have a difficult time identifying treated blues would certainly represent a major hit to the sapphire market and jewelry industry. This announcement by the AGTA laboratory is also very cautiously worded.
“Microscopic observations on one of these gemstones show indications of heating, and immersion in methylene iodide revealed a pale blue to near-colorless layer closely following the girdle outline. In other gemstones, a much deeper rim of light blue surrounding a deep blue core is seen. The interface between the core and the rim is undulating and delineated by a white line.
“The characteristics may be easily observed when the gemstones are viewed immersed in methylene iodide and illuminated through a diffused light source. This makes it relatively easy to identify the gemstones when buying or sorting. In addition, similar characteristics have been observed in two rubies.”
Richard Hughes, an expert in sapphires at Pala International, Fallbrook, Calif., reiterates that “the major identifying feature of these stones is a blue core surrounded by a diffuse colorless or near-colorless skin. This is best observed by immersion in methylene iodide [di-iodomethane] with a diffuse white plastic filter between the immersion cell and light source in the microscope.”
Hughes also notes that “all stones placed table down in an immersion cell will show some lightening of color at the girdle, since the stone is thinner at the girdle. But stones treated by this new process show a distinctive colorless rim that penetrates well into the gem, unlike the normal gradual lightening of color towards the girdle in untreated stones.”
Well, it doesn’t take a rocket scientist to realize that any gem treater who reads gemological literature on identification techniques will simply recut the gems to remove the outer layer. Then the labs will be back to square one in trying to identify any enhancement other than heat. But here’s the big worry: The research testing method that has identified beryllium-treated padparadschas, as time consuming and as expensive as it is, will not work with the new blues.
“SIMS analyses carried out on several gemstones have not, thus far, revealed a presence of beryllium,” says AGTA. “Further analyses are presently being carried out in an effort to fully characterize the process.
“We have received a great amount of help from U.S. and foreign dealers in providing information on how these gemstones have been treated. This has made the analysis process move along easily and quickly. If you suspect that you may have some of this material, you can submit it to our AGTA Gemological Testing Center.”
Ken Scarratt, director of the AGTA laboratory, is busy putting up more detailed information on the organization’s Web site. To see images of the new blue treated sapphires, and to find out more details about this enhancement, log onto www.agta.org. If you have information you think can be of help, please contact AGTA at (800) 972-1162 or e-mail: info@agta.org.
Two immersion photomicrographs of a stone treated by the new process have been posted on the AGTA Web site at the following URLs:
http://www.agta.org/newsflash/images/200310image1.jpg
http://www.agta.org/newsflash/images/200310image2.jpg
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