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
Parcels - Parcels of various types of Tourmaline
Parcels 2 - Parcels of various types of Tourmaline
Parcels 3 - Parcels of various types of Tourmaline
Parcels 4 - Parcels of various types of Tourmaline

Collector Tourmaline - Indicolite, bi colors, unusual & rare colors
Collector Tourmaline 2 - Indicolite, bi colors, unusual & rare colors
Special Tourmaline - Rare and unusual pieces
Huge Tourmaline - Top quality individual pieces

Chrome Tourmaline - Chrome Tourmaline
Indicolite Tourmaline - Blue, blue/green African, Brazilian
Multi & Bi Color Tourmaline - Nigerian, African, pink/green, blue/green

Tourmaline - Nigerian, various colors
Tourmaline 2 - Nigerian Tourmaline, African nodules
Tourmaline 3 - Kelly green, crystal green, Africa
Tourmaline 4 - Zambian nodules
Tourmaline 5 - Brazilian, various colors
Tourmaline 6 - Dravite, Mozambique
Tourmaline 7 - Sunset Tourmaline
Tourmaline 8 - Afghanistan Tourmaline
Tourmaline 9 - Afghanistan Tourmaline
Tourmaline10 - Schorl Tourmaline

Bargain Links:
Tourmaline Bargains
Indicolite Tourmaline Bargains

Return to Tourmaline Information Index

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