There are many named varieties. Usually, only the color determines the variety, but sometimes the composition as well. The main groups of gemstone quality are Schorl (Fe) - black, Dravite (Mg) - brown, Elbaite (Li) which has the following varieties: Achroite - colorless, Rubellite - pink, red, reddish-violet, Verdelite - green, Indicolite - blue, Siberite - violet, and Tsilaisite (Mn) - yellowish-brown, and Liddicoatite (Ca) - multicolored. Named after the locality in Brazil is Paraiba tourmaline, which has a very intense color partly created by a small amount of copper. Chrome tourmaline gets its color from chromium and more or less vanadium.

Physical properties:

Chemistry:  Na(Li,Al)3Al6Si6O18(BO3)3(OH)4
Hardness: 7 – 7½
SG: 2.98–3.20
Cleavage: None
Fracture: Low
Thermal sensitivity: Some

Optical properties:

RI: 1.62–1.64
Dispersion: 0.017 (medium)
Double refraction: 0.02 (medium)
Pleochroism: Strong (sometimes very strong)
Critical angle: 38°

Facet angles (pavilion/crown):

Vargas: 42°/41°
Olson: 40°/43°
Soukup: 43°/39°
Roth: 43°/39°
MDR: 43°/39°
Schlagel: 40°/36°
Hashnu: 42°/41°
Sinkankas: 40°/40°
GIA: 39°/43°
Perkins: 39°/43°
Raytech: 40°/39°
Cornwall: 42°/35°
Weikoff: 42°/39°
Carroll: 42.6°/35.3°

Cutting lap:

All grit sizes

Facet polishing:

Vargas: Aluminum oxide on tin/lead
Olson: Aluminum oxide on tin
Soukup: Aluminum or cerium oxide on tin/lead
Christiansen: Aluminum oxide on tin/lead, tin oxide on tin
Perkins: Diamond on BATT or Corian
MDR: Aluminum oxide on tin, tin or aluminum oxide on typemetal
Raytech: Aluminum oxide on Fast Lap, tin or phenolic

Cabochon polishing:

Christiansen: Aluminum, tin, or chromium oxide on leather or wood, diamond 50k/100k
Cox: Aluminum or chromium oxide on leather
Covington: Aluminum or chromium oxide on leather, diamond on canvas


According to the best color (unfortunately often in the C-axis, the short end). Sometimes the C-axis is "closed," meaning very dark, and a cut that allows little light transmission in that direction can make a stone that is less dark on the sides.


Many different variations of irradiation and/or heat treatments are used.


Long, narrow crystals are often more brittle and have more inclusions than round, grain-shaped pieces. Heat them gently or use cold dop.

Raw stones of Tourmaline

Tourmaline on Gemdat

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