Oregon Sunstone

A Labradorite feldspar from the plagioclase group with 68% albite and 32% anorthite. Copper gives color that is sometimes a clear red or green, sometimes dichroic (red and green) in the center of the stone. Copper sometimes forms quantities of small reflective plates that lie in bands (lamellar twinning). The Indian and Norwegian "sunstones" used for cabochon cutting are often classified as oligoclase but sometimes as labradorite. Inclusions are not copper but hematite or goethite.

Physical properties:

Chemistry: Na[AlSi3O8] Ca[Al2Si2O6]
Hardness: 6-6½
SG: 2.71-2.73
Cleavage: Perfect, three directions
Fracture: Conchoidal to uneven, somewhat brittle
Thermal sensitivity: None

Optical properties:

RI: 1.56-1.57
Dispersion: 0.012 (weak)
Double refraction: 0.008 (weak)
Pleochroism: None
Critical angle: 41°

Facet angles (pavilion/crown):

Vargas: 44°/42°
Olson: 43°/42°
Soukup: 43°/42°
Roth: 43°/42°
MDR: 43°/42°
Schlagel: 43°/39°
Hashnu: 43°/42°
Sinkankas: 43°/40-50°
GIA: 43°/42°
Perkins: 43°/39°
Raytech: 43°/42°
Cornwall: 44°/37
Weikoff: 44°/42°
Carroll: 43°/35.3°

Cutting lap:

Medium or fine grit

Facet polishing:

Vargas: Cerium oxide on acrylic, Aluminum oxide on tin/lead
Olson: Tin oxide on acrylic
Christiansen: Aluminum oxide on tin/lead, Cerium oxide on acrylic, Tin oxide on tin
Perkins: Aluminum oxide on BATT or Corian
Raytech: Cerium oxide on Fast Lap, phenolic or acrylic

Cabochon polishing:

Olson: Tin oxide on felt
Christiansen: Aluminum/cerium oxide on leather or felt
Cox: Cerium oxide on felt
Covington: Cerium oxide on felt


Yellow stone without orientation pattern. With moderate schiller, banding parallel to the table facet. With strong schiller, orient the banding perpendicular to the table facet to achieve a red stone or to cut a cabochon. Stones with red or green color centers should be oriented with the most color in the crown. Often, even the table facet does not need to be oriented away from the plane of the cleavage plane.


None known


Sometimes it can be difficult to polish - try using a LightningLap CeOx for better results.

Here is a link to a great page on how to orient Oregon Sunstone. http://doubleeaglemine.com/Cuttingtips.html

Oregon Sunstone rough

Sunstone on Gemdat

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