Achroite Tourmaline

Color: (Greek - without color) colorless or nearly so, fairly rare
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: Medium (.017)
Heat Sensitivity: Can be, but usually no problems
Dichroic: Strong (many color variations), on colorless material obviously not generally present
Birefringence (double refraction): Medium (.014-.024)
Crystal structure: Hexagonal

Treatments: Heat treating to lighten colors is common and sometimes material will go clear (Achroite).

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 not needed on clear colorless rough, cut on the "c" axis if it is convenient. Sometimes you can find a piece of rough like the stone above that has a spot of color surrounded by clear. This type of stone is fairly uncommon but as you can see makes a very interesting finished gem if you can find one. Orientate the color spot in the middle of the stone, below the girdle line and toward the tip of the pavilion. Be sure and check the color spot from all directions before cutting, so that it is centered up.

Design Notes: About any deep Tourmaline designs will work 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

Rough Links:
Tourmaline - Index of Tourmaline Rough
Collector Tourmaline - Blue/Green Bi Color Tourmaline crystal from Nigeria, Top Tri Color Tourmaline crystal from Afghanistan, Elbaite (watermelon) Tourmaline from Nigeria, Maine Tourmaline USA, Chrome Tourmaline from Tanzania, Stewart Hot Pink Tourmaline from California, Siberite Tourmaline
Huge Tourmaline - Unusually large crystals and pieces of Tourmaline
Indicolite Tourmaline - Large Indicolite Tourmaline crystals from Nigeria, Indicolite Blue/Green Tourmaline from Nigeria, Indicolite Tourmaline from Nigeria
Multi & Bi Color Tourmaline - Green/Blue Bi Color Tourmaline crystals from Nigeria, Bi Color Tourmaline
from Nigeria, pink/green Tourmaline, blue/green Tourmaline, clear/pink/green Tourmaline
Tourmaline - Nigerian Tourmaline Parcels, Nigerian Tourmaline Mix, Huge Nigerian Tourmaline, Rubellite Tourmaline, Achroite Tourmaline, Dravite Tourmaline, Verdelite Tourmaline
Tourmaline2 - Brazilian Tourmaline Mix, Afghanistan Pastel Tourmaline, Pink Rind Brazilian Tourmaline, Mozambique green/yellow Tourmaline, Peach Mauve Brazilian Tourmaline, Siberian Bi-Color from Siberia, Zambian Tourmaline, Sunset Tourmaline from Kenya, Rubellite Tourmaline, Achroite Tourmaline, Dravite Tourmaline, Verdelite Tourmaline
Tourmaline3 - Kelly Green Tourmaline from Nigeria, Nigerian Green Tourmaline from Nigeria, African Green Crystal Tourmaline, Brazilian Green Crystal Tourmaline, Verdelite Tourmaline
Tourmaline4 - Zambian Tourmaline Nodules from Zambia, Rubellite Tourmaline, Achroite Tourmaline, Dravite Tourmaline, Verdelite Tourmaline
Tourmaline5 - Crystal Green Tourmaline from Nigeria, Green Crystal Tourmaline from Nigeria, Verdelite Tourmaline
Tourmaline6 - Dravite, Sunset Tourmaline, Mozambique
Tourmaline Parcels - Parcels of various types

Bargain Links:
Tourmaline Bargains
Indicolite Tourmaline Bargains

Return to Tourmaline Information Index

E-mail to inquire or order: jeff@faceters.com