Piece of Glass and Two Lab Growns among "Natural" Sapphires
September 11, 22
(IDEX Online) - A parcel of "natural" sapphires submitted for grading included a 48.63-ct piece of glass and two lab grown stones.
The Gemological Institute of America (GIA) described the selling of simulants and synthetics mixed with natural stones as "an old form of deception".
It usually happens close to mines, where inexperienced buyers assume the gemstones come directly from the source—and where advanced testing is likely not available prior to the purchase.
The GIA's lab in Carlsbad, California, USA, received four blue rough stones submitted as natural sapphire for identification and origin reports.
The largest, viewed under a microscope, turned out to be "a glass imitation". Two others, weighing 9.17-cts and 6.21-cts, were identified as as laboratory-grown sapphires coated with resin.
The fourth stone, weighing 8.46-cts, turned to be "a natural sapphire, heat treated, with Madagascar as the country of origin".
"This was an interesting study of how synthetics and simulants can be mixed with their natural counterparts to misrepresent a parcel," said the GIA in its Lab Notes, Gems & Gemology, Summer 2022.
"However, careful examination and standard gemological testing are usually enough to identify them correctly."
Pic courtesy GIA. The only natural sapphire is on the extreme right.