The Gemological Institute of America (GIA) will host its next Gemstone Gathering on March 28 in Bangkok, Thailand. Laurent Massi, GIA education director in Thailand, will present “Phenomenal Gemstone Phenomena” by defining and classifying optical and structural effects that add to a gemstone’s allure.
From star rubies to the Usambara effect to chameleon diamonds, Massi will focus on the nomenclature of gemstone phenomena. For example, alexandrite has the ability to change colour according to the type of light that illuminates it; asterism exhibited by gemstones such as star rubies and star sapphires display a six- or 12-ray star that moves on the top of the stone when properly illuminated and cut as a cabochon; and a chameleon diamond can reversibly turn from green to orange or yellow when placed in light or after gentle heating.
Massi will discuss optical and structural effects of gemstones by breaking them down into four broad categories namely colour-change effects, which are primarily a result of light, temperature or thickness; chatoyant effects, which are the result of inclusions and the interaction of light; asterism, a result of inclusions and the interaction of light; and other optical effects such as iridescence, adularescence and aventurescence.
Massi has given gemmology lectures across the globe and has published various scientific and educational articles. His recent piece on the new gem mineral hibonite, one of the rarest gems on earth, was featured in GIA’s Gems & Gemology.
Massi completed his PhD studies on “Atomic-scale defects in brown and hydrogen-rich diamonds” at Nantes University’s Department of Physics in France and is a Graduate Gemmologist.
GIA’s Gemstone Gathering in Thailand is a free event that begins at 6 pm on March 28 at the Crowne Plaza Hotel in Bangkok.
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