Dispersion: Low (.012), but the combination
of a high polish and minute inclusions can simulate the effect of moderate
Heat sensitivity: Low
Birefringence (double refraction): Weak to
Crystal structure: Triclinic (bytownite,
labradorite and sunstone) Monoclinic (orthoclase).
Cutting: Cleavage usually doesn’t present
a problem. Sharp corners have the tendency to chip out when cutting.
Polishing: Cerium oxide on most common laps.
Comments: If cutting an Oregon sunstone with
a pocket of color, put the colored area at the culet of the stone. This will
impart the color to the rest of the stone. If there is strong shiller, then it
will be better to cut the stone as a cabochon.