Tijgerijzer Weight: ± 1.20 CT. Size: 7x5 mm Shape: Oval Cabochon Color: Metallic Red Brown Clarity: Opaque Luster: Astonishing Sharp Tigers Eye Origin: Russia Hardness: 7 Specific Gravity: 2.65 - 2.91 Refractive Index: 1.544 - 1.553 Chemical Composition: SiO2 , Silicon Dioxide Crystal Structure: Trigonal Treatment: None