Sunstone Facet / Faceting Information


Sunstone Facet / Faceting Information

Sunstone (Feldspar)

Shiller Sunstone carvineg

Color: Sunstone Colorless, champagne, Schiller (copper inclusions, usually used for cabochons), Multi colored (green, blue, red, orange), red
Moh’s Hardness: 6-6.5
Refractive Index: 1.52-1.568
Critical Angle: 41.14°
Specific Gravity: 2.56-2.70
Cleavage: Perfect
Fracture: Uneven, somewhat brittle
Dispersion: .012
Heat Sensitivity: Moderate in my experience
Dichroism: Weak
Birefringence (double refraction): Weak to medium (.005-.01)
Crystal Structure: Triclinic

Treatments: Generally none

What I prefer to polishing with: Cerium oxide with a Spectra Ultralap.

Jeff’s Comments: Cuts and polishes easily, use a medium fine lap like a 600 grit for roughing in because a coarse lap can sometimes aggravate cleavage. Cleavage usually is not a problem, sharp corners have a tendency to chip out sometimes during cutting. Orientation of color zones is important, put the zone(s) in the center of the stone about level or slightly below the girdle. Be careful and orientate for the best color through the table.

Design Notes: About any Quartz design will work well. I prefer a deeper design and often cut Barions.

Design Links: Tzar – High dome will help improve color and sparkle

Gram Faceting Archive of Information
This edited version of an article by the late Jeff Graham is part of a special archived informational series from Gram Faceting. Used with permission.