Robijn (Thailand) ± 0.05 CT. 3x1.5 mm Marquise Cut Color: Fine Blood Red Clarity: Slight Inclusion Luster: Ravishing Origin: Thailand Hardness: 9 Specific Gravity: 3.9 - 4.1 Refractive Index: 1.76 - 1.78 Chemical Composition: Al2O3, Aluminum Oxide Crystal Structure: Trigonal