Gadolinium Gallium Garnet (GGG) Color: Colorless, yellow, green, blue, pink, purple, red and orange
Moh’s Hardness: 7
Refractive Index: 1.97 – 2.02
Critical Angle: 30.51°
Specific Gravity: 7.02
Heat Sensitivity: Low
Birefringence (double refraction): None
Crystal Structure: Isometric
What I prefer to polishing with: Tin lap with Alumina oxide. Zinc laps with 8,000 pre-polish and 50,000 polish.
Jeff’s Comments: Cuts and polishes like Garnet. It is quite pretty especially in clear and light colors.