AGTA writes:
In recent months, blue sapphires reaching the US market show indications that they are being treated by a new technique. Most of the gemstones are coming from Sri Lanka, and they range in size (s) from 2 carat to 17 carats.
Microscopic observations in sample specimens show indications of heating, and immersion in methylene iodide reveal 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 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.
SIMS analyses carried out on several gemstones have not, thus far, revealed a presence of beryllium. Further analyses are presently being carried out in an effort to fully characterize the process.
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