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Colorless Gemstones

 

 


Gemstone Crystal System Density Hardness Refractive index Treatments
Beryl hexagonal 2.72 7.5-8.9 1.577-1.583 heat, radiation, fracture filling, oiling
Corundum trigonal 4.00 9.0 1.762-1.770 none
Diamond cubic 3.52 10 2.417 radiation, drilling, fracture filling
cubic 2.29 6.00 1.483-1.487 none
Moonstone monoclinic 2.56 6.0-6.5 1.518-1.526 none
Opal amorphous 2.15 5.0-6.5 1.450 fracture filling
Quartz hexagonal 2.66 7.0 1.544-1.553 fracture filling
Sapphire hexagonal 4.00 9 1.762-1.770 heat, fracture filling
Spinel cubic 3.60 8 1.718 none
Topaz orthorhombic 3.53 8 1.619-1.627 blue is irradiated
Tourmaline trigonal 3.06 7.0-7.5 1.624-1.644 heat
Zircon tetragonal 4.00 6.50 1.810-1.815 none