Gem/Gem Topic of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

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January, 1998 (Revised, August, 2004)

Oregon Sunstone

Prior to the finds of substantial amounts of facetable crystals in Oregon, most sunstone, much of which came from the Orient, was used for cabbing material, or in the production of pale yellow, low value, faceted goods. Such is the case no longer. An incredible variety of high value sunstone rough is now being extracted by several mining companies as well as on public collecting sites in Oregon. Two main features are notable in rough collected from this location: 1) strong body colors ranging from pinks and tans to oranges, greens and reds as well as bi- and tri-colors, and 2) fine grained coppery shiller which allows for transparency in the stone yet still produces the phenomenon of aventurescence or "glitter". Every combination of shiller or lack of it and color is found.

 

Shiller Pale yellow

Bicolor

 

Red Green 80

 

Collectors and jewelry lovers from all over the world are fast becoming aware of this uniquely American gemstone and appreciate it as one of the shrinking number of materials that can be correctly assumed to be completely untreated and natural.


Value

Because there are so many different kinds of sunstone, the values range widely. The least valuable form is the pale yellow to colorless non-shiller type which in native cut, or calibrated stones may go for a few dollars per carat and for custom cut stones somewhat more. The pinks and tans with and without shiller have additional value, depending on the effect. The opaque cab-type stones are modestly priced. Some greens, strong pinks and reds as well as the bicolored and tricolored stones with and without shiller are offered much more valuable. The most desirable color is red with large (over 3 carat) stones of prime color retailing at prices rivaling fine sapphires and emeralds. The best greens are very rare and may cost more than the best reds. Sunstone is often used for carving material; and the carvings are valued as much for their artistic merit (and the fame of the artist) as for the value of the material itself.

Gemological Data

Makeup: a calcium rich species of plagioclase feldspar,

sometimes with copper or hematite inclusions and traces of iron; 32% Albite, 68% Anorthite

Luster: Vitreous

Hardness: 6 - 6.5

Cleavage: 2, Perfect

Fracture: splintery to uneven

Density: 2.70

RI: 1.56 - 1.57

All text and images, unless otherwise designated, © 2004 Barbara Smigel


Stones Currently Available:

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Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment