![]() MASSIVE DAZZLING X RAYS BLACK STAR SAPPHIRE GEMSTONE. ![]() ![]() Note that the type of dopping varnish is of a color that matches the stone. MASSIVE DAZZLING 6 RAYS BLACK STAR SAPPHIRE OVAL CABOCHON GEMSTONE WITH GLC CERTIFY 11.09 CT. It is because of this parting that the stones get filled with dopping varnish, to conceal large holes in the base. It is only the basal parting that comes into play with black star sapphires, because the exsolved hematite that causes the lack of adhesion is only in the basal plane. In Thailand, one often sees cavities on the back of black star sapphires filled in with brown dopping varnish. Rutile and ilmenite/hematite exsolve in different directions: rutile along the second-order hexagonal prism. It is a very desirable gemstone due to its excellent color, hardness, durability, and luster. Unlike other star sapphires and rubies, the asterism in these stones generally results from the exsolution of ilmenite (FeTiO 3) and/or hematite (α-Fe 2O 3) instead of rutile (TiO 2). Sapphire is the most precious and valuable blue gemstone. Photo by Wimon Manorotkul.īlack star sapphires primarily come from Kenya, Australia, and Thailand. The 75 ct black star sapphire that was brought in for testing. Comprehensive CAD/CAM For Jewelry Certificateįigure 1.
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