Natural Lapis Lazuli, Approx. Weight (ct) : 13.65 Cts. Shape : Pear, Size/Dimension : 22 x 13 MM Depth : 6.2 MM , Color : Blue , Clarity : Opaque , Luster : Good , Origin : Afghan, Hardness : 6.5, Specific Gravity : 1.5 Refractive Index : 1.522 - 1.530 , Chemical Composition : Na,Ca)8(Al,Si)12O24(SO4)Cl2(OH)2, Treatment : Natural