Color: Blue, sometimes with a hint of green
Moh’s Hardness: 7-7.5
Refractive Index: 1.616-1.652
Critical Angle: 38.23°
Specific Gravity: 3.02-3.26
Fracture: Uneven, small conchoidal.
Heat Sensitivity: Can be delicate and care must be taken when dopping with heat and wax.
Dichroic: Strong (many color variations)
Birefringence (double refraction): Medium (.014-.024)
Crystal structure: Hexagonal
Treatments: Generally not treated, but sometimes heated to lighten dark rough…
What I prefer to polishing with: Alumina oxide with a tin lap (scored).
Jeff’s Comments: Cuts and polishes like any other Tourmaline… Can be problematic, some rough seems to be under stress and it is not unusual to have fractures show up during cutting. Some rough from certain locations is very brittle (maybe from heating, there is no way to be sure). Orientation is important, go for the best color, “c” axis is often closed or dark.
Design Notes: About any Tourmaline design will work well, although I generally prefer a shallow checkerboard on darker rough. My Smith Bar is a very good choice for dark axis “c” rough. Also most of my reflector designs work very well…
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