Witte Topaas ± 0.55 CT. 6x4 mm Ovaal Top White Clarity: Clean To Eye Clean Luster: Outstanding Origin: Brazil Hardness: 8 Specific Gravity: 3.4 - 3.5+ Refractive Index: 1.61 - 1.64 Chemical Composition: Al2SiO4(F,OH)3, Aluminum Silicate Fluoride Hydroxide Crystal Structure: Orthorhombic Treatment: None