Color: All ranges, including color changes
Moh’s Hardness: 8.25-8.5
Refractive index: 2.14-2.20
Critical Angle: 27.86°
Specific Gravity: 5.7
Fracture: Sub-conchoidal, brittle
Heat Sensitivity: Low
Birefringence (double refraction): None
Crystal Structure: Isometric
What I prefer to polishing with: Zinc laps with 8,000 pre-polish and 50,000 polish.
Jeff’s Comments: CZ manufactured in the US and Britain is generally more consistent and having less polishing problems.