Diopside (Calcium magnesium silicate)
Color: Chrome green to colorless.
Moh’s hardness: 5-6
Refractive index: 1.671-1.726
Critical angle: 37°
Specific gravity: 3.27-3.31
Heat sensitivity: Low
Pleochroism: Dichroic – weak (green to olive green).
Birefringence (double refraction): Medium (.028)
Crystal structure: Monoclinic
Cutting: Orient stone to avoid cleavage plane. Use an extra-fine lap for pre-polishing. Cutting perpendicular to the crystal is slow to difficult.
Polishing: Alumina or cerium oxide on most standard polishing laps or chrome oxide Ultralap.