Siberite Tourmaline Faceting Information

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Siberite Tourmaline Faceting Information

Siberite Tourmaline

Siberite rough

Color: Blue/purple
Moh’s Hardness: 7-7.5
Refractive Index: 1.616-1.652
Critical Angle: 38.23°
Specific Gravity: 3.02-3.26
Cleavage: None
Fracture: Uneven, small conchoidal.
Dispersion: .017
Heat Sensitivity: Sometimes
Dichroic: Strong (many color variations)
Birefringence (double refraction): Medium (.014-.024)
Crystal structure: Hexagonal

Treatments: Generally there is no treatments with this kind of rough.

What I prefer to polishing with: Alumina oxide with a tin lap (scored).

Jeff’s Comments: Cuts and polishes like any other Tourmaline, usually no problems. This material is quite rare and is seldom flawless.

Design Notes: About any Tourmaline design will work well, although I generally prefer a shallow checkerboard on darker rough.

Design Links: Signature #4 – This is good for about any rough
Easy Emerald – This is a classic and works well on poor “c” axis colored stones
Smith Bar – This is a classic and works well on poor “c” axis colored stones

Gram Faceting Archive of Information
This edited version of an article by the late Jeff Graham is part of a special archived informational series from Gram Faceting. Used with permission.