Labradorite Facet / Faceting Information


LabroditeLabradorite (Feldspar)

Color: Pale yellow to gray with play of color, quality material has a rainbow like sheen
Moh’s Hardness: 6-6.5
Refractive Index: 1.52-1.568
Critical Angle: 41.14°
Specific Gravity: 2.69-2.70
Cleavage: Perfect
Fracture: Uneven, somewhat brittle.
Dispersion: .012 (Considered low, but the combination of a high polish and minute inclusions can simulate the effect of moderate dispersion).
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. Orientate the sheen up through the table if there is schiller present.

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.