Gemstone Type : Natural Golden Black Star Sapphire 6 Rays Approx. Weight (ct) : 1.65 Cts. Shape : Oval Cabochan Size/Dimension : 8 x 6 MM Depth : 3 MM Color : Black Clarity : Opaque Luster : Fine Origin : Thailand Hardness : 9 Specific Gravity : 3.9 - 4.2 Refractive Index : 1.76 - 1.79 Chemical Composition : Al2O4 Treatment : Natural