Zirkoon Approx. Weight: 1.35 CT. Size: 5.5 mm Shape: Round Cut Color: Orange Clarity: Clean Luster: Stunning Origin: Cambodia Hardness: 7.5 Specific Gravity: 4.6 - 4.7 Refractive Index: 1.92 - 2.01 Chemical Composition: ZrSiO4, Zirconium Silicate Crystal Structure: Tetragonal