Gemstone Type : Natural Tourmaline Approx. Weight (ct) : 3.20 Ct. Shape: Oval Cabochan Size/Dimension (LxHxW) : 10 x 8 x 5 MM Color : Green Clarity : Transparent Luster : Outstanding Origin : Africa Hardness : 7.5 Specific Gravity : 3.0+ Refractive Index : 1.62 - 1.68 Chemical Composition : Na(Li,al)3al6si6o18(Bo3)3 (oh)4