Host: The Gemmological Society of Japan
Pages 17
Sapphires displaying a golden sheen are known as “gold sheen” sapphires in the trade. Gold sheen sapphires are believed to be mined at northeastern Kenya (Bui et al., 2015). Here we report the chemical characteristics and compare with various sapphire sources including other gold sheen sapphire data previously documented. Inclusions observed in our samples are similar to those in other gold sheen sapphires documented in previous studies. Twenty-three samples were tested with LA-ICP-MS at GIA’s Tokyo laboratory, and they showed high Fe, low V contents and high Ga/Mg ratio. Samples in this study are similar to other gold sheen sapphires in Fe, Ga and V contents. The similarities indicate that these gold sheen sapphires possibly come from the same origin. Considering Kenya as a possible origin, two different types of sapphire deposits, basalt-related (Lake Turkana) or syenite-related types (Garba Tula), are known. Sapphires from both deposits are similar in Fe and Ga contents to each other, but different in V contents. Gold sheen sapphires are close to those from Garba Tula deposits in chemical features. More gemological and chemical studies are required for constructing the database for origin determination.
