While feldspar sunstones from sources around the world have been used for carvings and cabochons, Oregon sunstone material has proven to be facetable as well. Substantial amounts of high-value Oregon sunstone rough are now being extracted from its namesake state. Oregon sunstone is a variety of labradorite that frequently displays a stunning aventurescence, or “glowing” or “glittery” schiller effect, caused by copper inclusions. Although intense red and transparent stones with schiller are very desirable, many color varieties are found in Oregon, with and without the glowing effect.
Oregon Sunstone Value
Pale yellow to colorless, non-phenomenal Oregon sunstones, whether native cut or calibrated stones, may go for a few dollars per carat to $20 per carat for a custom cut.
Pinks and tans, with and without schiller, commonly range up to $50 per carat, depending on the effect. Opaque cab-type stones are modestly priced. Some greens, strong pinks, and reds, as well as bicolored and tricolored stones, with and without schiller, range from $50 to $300 per carat.
Large stones (over three carats) with an intense red color may retail for as much as $1,700 per carat. The best greens are very rare and may cost more than the best reds.
Carved Oregon sunstone pieces are valued as much for their artistic merit as for the material itself.
Aventurescence or schiller effect. (See “Identifying Characteristics” below).
Formula
Oregon sunstone is a variety of labradorite, a mineral in the plagioclase feldspar solid-solution series, with a composition of 32% albite (NaAlSi3O8) and 68% anorthite (CaAl2Si2O8).
Gem collectors and jewelry lovers from all over the world are fast becoming aware of this uniquely American gemstone. While many varieties of feldspar can display aventurescence and are referred to as “sunstone,” this effect is typically caused by inclusions of hematite or goethite. The labradorite sunstones found in Oregon have inclusions of copper. This unique happenstance means these gemstones may both display a schiller effect and transparency. This makes these gems highly desirable as faceted jewelry stones.
Although a relative newcomer to many in the gem buying public, Oregon sunstone has traditionally been valued and traded by the Native Americans of the Pacific Northwest. In 1987, Oregon officially declared it its state gemstone. In the esoteric realm of birthstone mythology, sunstones are considered the phenomenal birthstone for those born on Sunday.
Although they share a name (and pleochroism, the showing of two or more colors when viewed from different angles), Oregon sunstones are not the so-called “sunstones” Vikings reputedly used to navigate on overcast days or when the sun was low in the Arctic sky. Pleochroic iolite was most likely the “Viking Compass.”
The only feldspar sunstone with copper inclusions is Oregon sunstone. However, not all specimens display the schiller effect. The copper inclusions in Oregon sunstone come in four different varieties: threads, spots, sheets, and clouds.
Pleochroism
Stone Color
Pleochroism
Yellow
colorless/light yellow
Red-orange and blue-green
blueish green/light red
(multicolored)
violet /reddish orange
Blueish green
blueish green/light orange/ colorless
Red orange
orange/light reddish purple
Orange
orange/reddish orange
Yellowish green
blueish green/light orange
Blue-green and violet
red-violet/reddish orange/ blueish green
Synthetics
Oregon sunstones have not been synthesized. However, goldstone, a synthetic material made of glass with copper inclusions, may be used as a simulant. A gemologist can easily distinguish a natural Oregon sunstone from one of these pieces.
Enhancements
Although plagioclase feldspars such as andesine can be enhanced with the addition of copper through heating and pressure treatments, Oregon sunstone is not known to be enhanced or treated. It acquires its copper naturally.
Sources
Oregon sunstone has been found in Harney County and Lake County, Oregon. Most of this material is mined by companies on private claims. However, there is a public Sunstone Collection Area in Lake County.
Because of their hardness rating of 6 to 6.5, Oregon sunstones are best suited for jewelry such as pendants, earrings, brooches, or other pieces that won’t endure heavy wear. Common dust has a hardness of 7 to 7.5 and will scratch this material. Steel can scratch gems with a hardness of 6.
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