Zoisite and Tanzanite Faceting Information

All the resources needed for Tanzanite faceting. Information such as successful tips, tricks and details to help learn more on Tanzanite stones and facets.


Tanzanite and Other Gem-Quality Zoisite

Tanzanite step cut

Color: Blue, violet, purple, orange, brown, colorless and pink, also some collector colors
Moh's Hardness: 6-6.5
Refractive Index: 1.691-1.70
Critical Angle: 36.28°
Specific Gravity: 3.10-3.37
Cleavage: Perfect in 1 direction
Fracture: Uneven, brittle
Dispersion: .030
Heat Sensitivity: Moderate
Pleochroism: Trichroic - strong. Blue to purple to orange or brown
Birefringence (double refraction): Weak (.006-.009)
Crystal Structure: Orthorhombic

Treatments: Usually heat-treated to change color from orange/brown to blue/purple

What I prefer to polishing with: Alumina oxide on a Tin lap, Spectra Ultralap, 8,000 diamond, 50,000 diamond polish on a Zinc laps

Jeff's Comments: If cutting before heating orientate the best coffee color up through the table (it will be the best color when heated). Tanzanite can be very brittle and chips easily along keels. I prefer to cut only preheated material because there is some material that will not change to blue/purple. Rough is difficult to find clean.

Design Notes: About any Quartz, Tourmaline or Peridot (and of course Tanzanite) design will work well. As the rough gets more saturated I prefer checker board designs. For light rough I like deep brilliant designs.

Design Links: Cornered -This will work nicely in darker rough

Jeff R. Graham

The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.

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