Dravite Tourmaline Facet / Faceting Information

Dravite step cutDravite Tourmaline

Color: Brown, yellow-brown, orange-brown and reddish-brown
Moh’s Hardness:
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: Not usually a problem
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… Orientation is important, go for the best color. Often there is a yellow/brown and a brown/darker brown direction. Orientate the darker color like you would a closed “c” axis…

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.