Oregon Sunstone is the name given to facetable, gem-quality Labradorite which is colored primarily by Copper. These untreated gemstones include rare jewels which come in a fantastic variety of natural colors, optical effects, and types.

History...

Oregon Sunstone was formed in ancient basalt lava flows. As the basalt weathered away, the crystals were released. Early residents of the area around Plush, Oregon came across the crystals lying on the ground, and they may still be found that way.

These gems first appeared on the market early in the 20th Century, with the stones being sold under the name "Plush Diamonds." They were popular for a time, particularly in San Francisco. Tiffany & Company bought up the claims, but did little to exploit the gem commercially.

The gem began to reappear after the old Tiffany claims were sold off and mining restarted under new owners.  Claims also began to be worked in the surrounding area. In 1987, Oregon Sunstone was named as the official gemstone for the State of Oregon. Then, in 1988, a second large deposit near Burns, Oregon began to be exploited.

Names...

Oregon Sunstone is often confused with Oligoclase (India) Sunstone. Though related, these are not the same type of gemstone - either in the makeup of the mineral or in appearance.

You can sometimes find Oregon Sunstone listed as "Andesine," "Red Labradorite," "Andesine Labradorite," "Oregon Feldspar" or "Feldspar Labradorite."

You should avoid confusing the untreated, natural Oregon Sunstone varieties of Labradorite and Andesine with the artificially colored Andesine and Labradorite gems coming out of Asia (see below).

Technical...

All Oregon Sunstone are members of the Feldspar group of minerals.

They are classified as Plagioclase Feldspar, with most falling into the Labradorite sub-group. Unlike most Labradorite, the Oregon Sunstone variety is transparent, and is colored by Copper.

Some Oregon Sunstones contain slightly more Sodium, and less Calcium, which puts those into the Andesine (rather than the Labradorite) classification. Such stones can come from the same mines as the Labradorite variety.

The stone has perfect cleavage in two directions, making crystals vulnerable to cracking during extraction. Although some are mined by crushing the hard surrounding matrix, this can result in many larger stones being fractured. Most choose to sift and gently dislodge the gems from soil and degraded rock.

Hardness of Oregon Sunstone ranges from 6.5 to 7.0 on the Mohs scale, making it suitable for a wider variety of jewelry types, than softer, gems in the Feldspar family.

Variety of Colors...

Yellow and Clear - Yellows are usually lighter. They sometimes are slightly brownish (straw). Often the yellow is so pale that the stone is nearly water-clear. Water-clear stones are fairly uncommon.

Yellow Oregon Sunstone (the peach is a reflection)

Pink - pink can be either the stone's base color, or be produced by a haze of Schiller. This color usually tends slightly toward orange. Light Red is sometimes described as Pink, and vice versa.

Orange - these shades vary from orange-yellow to orange-red. They are often described as "Copper," "Copper-Red," or "Peach" (yellow-orange).

Rootbeer - deep reddish-brown caused by red and green mixing.

Red - reds vary from slightly orange, to almost pure red, to slightly blue (plum). The intensity is described as Light, Medium or Dark.

Oregon Sunstone Reds

Greens - coppery greens can vary between dark grass green to yellowish green, to bluish green. 

Teal

Blue - the blues encountered usually tend towards teal or turquoise shades.

Bi-colored and Tri-colored - these terms refer to two or three color zones present in a single stone.

Tri-Colored Gem

Dichroic/Trichroic - gems with these characteristics display two or three colors respectively. The color displayed changes depending on the orientation of the stone. This effect is known as Pleochroism.

Stone Showing Pleochroism

Watermelon - this term describes stones with distinct zones of pinkish red and green.

Color Change - a stone which changes color, depending on the light source (e.g., between fluorescent and incandescent lighting). This effect is often confused with Pleochroism.

Schiller...

Many Oregon Sunstones exhibit a metallic flash known as Schiller which is caused by microscopic flecks of copper aligned in layers. The sparkling Schiller can be orange, copper red, pink, silver or green. This can make for a very interesting stone, particularly when the Schiller forms a pattern which flashes only from certain orientations, but is otherwise invisible.

Pink Schiller catching sunlight in a Trichroic Stone

The Schiller stones are extremely varied, and many of the more interesting feature one-of-a-kind patterns. Other stones present a nearly solid reflective mirror when viewed from certain angles. Quality of cutting can make a huge difference in whether a Schiller Oregon Sunstone exhibits desirable sparkles and flashes, or whether it gives a less desirable impression of being flawed and dull. Even duller stones can have interesting characteristics, although these may be more attractive to collectors than for use in jewelry.

What to Look for...

Just as for diamonds, the 3 C's (Clarity, Cut and Color) are important for Oregon Sunstones...

• Clarity...
  Stones should not contain veils, dull streaks, cracks or inclusions visible with the naked eye. The exceptions are those stones which exhibit desirable copper Schiller platelets, which are not considered flaws in this gem.
• Cut...
  Look for well-cut stones. Oregon Sunstones are often available in custom cuts, which can be spectacular. Beautiful carved examples are also seen from time to time, which can show off stones which contain multiple colors or interesting areas of Schiller.
   
  On the other hand, in poorly oriented stones, any Schiller can appear as dull streaks instead of glittering jets or mirror-like flashes. Bad cutting can also cause gems having multiple color layers to appear a lifeless brown or grey. And unless the facets are the correct angle, much of the sparkle will be lost.
• Color...
  Color is very important in establishing the value of an Oregon Sunstone. Strong colors are preferable to weak, washed-out, or muddy tones. Some colors and color combinations are rarer, some much more so. When comparing equally intensely colored gems, here is how different colors stack up against each other in value:
  
  Saturated transparent reds have traditionally commanded very high prices. Scarcer still are green, teal blue, and aqua stones, with intense shades encountered even less often.
  
  Pink, clear, straw, orange and yellow stones are more readily available. For multiple stone settings, it is easier and more affordable to create matched sets of gems using these colors. These colors are also more commonly found in calibrated sizes which makes it easier to match a stone to a pre-made setting.
  
  Stones containing  two or more colors are sometimes offered, and these can be quite interesting and attractive when well-cut. Stones having a watermelon effect, with a pink-red center surrounded by a green rind, are usually snapped up quickly.
  
  Another rarity are the Dichroic or Trichroic gems (which change between 2 or 3 colors respectively as the stone is moved - an effect is also known as pleochroism). Color change gems have also been found, and they are also quite rare. Like Alexandrite, color change sunstones display different colors, depending on the type of light (sunlight, incandescent, etc.).
  
  Other color combinations in layers can be cut to combine the colors to produce a third shade when viewed through the stone's face.

Be Aware...

Confused With: Other "Sunstones," particularly Oligoclase and Orthoclase varieties of Feldspar, are sometimes mislabeled as Sunstone from Oregon. You can usually tell by the appearance - the Schiller in Sunstones from other areas is coarse and heavier, and the color and clarity characteristics may also be suspiciously different.

And although some Oregon Sunstone is Andesine Feldspar, not all Andesine is from Oregon. Stones of this type from other areas are sometimes mistakenly said to have originated in Oregon. Conversely, some Andesine and Labradorite Feldspars from Oregon mines is sometimes sold as being from some other area.

"Golden Sunstone" is another Labradorite, which is mined in Mexico and marketed under this name. It very closely resembles some of the yellow Oregon Sunstones. However, it gets it color from Iron, rather than Copper. Some of this material can have inclusions which have been termed "silver schiller." This can be attractive, but more resembles inclusions in the oligoclase sunstone types, rather than Oregon's Labradorite or Andesine varieties. Its uniform appearance makes it desirable to jewelry manufacturers and wholesalers, which demand large quantities of identical stones.

Substitutes and Enhancements: Oregon Sunstone is a natural material. No treatments or enhancements are known for the Oregon material, and man-made versions are currently too expensive to make synthetics economical to produce. It is possible that such simulants might be introduced, however. Be aware of the source of your stone. Some glass with glittery inclusions and Dichroic glass have been sold with an "Oregon Sunstone" or "Sunstone" label, but this is usually not deceptively used, but rather to describe the color or effect. It is possible that someone may attempt to substitute for Oregon Sunstone, some of the controversial highly colored Andesine, Labradorite, and "Andesine Labradorite" which has been deceptively marketed as natural, untreated from the Congo, Tibet, Mongolia, etc. According to recent reports, this is common brown-yellow Labradorite which is highly treated by an extensive heating and copper diffusion process. A large amount of this has made its way into the U.S., France and other countries. The silky "schiller" (as opposed to Oregon Sunstone's coppery platelets) exhibited by some of these treated stones may be evidence of heating and/or residue from treatment. Bicolored treated stones also show a green center surrounded by red, the opposite of the natural watermelon stones. Other indicators of treatment can be seen under high magnification.

Durability: Oregon Sunstone has perfect cleavage in two directions. This can make it vulnerable to hard blows. Rings and bracelets containing the stone should not be worn in situations where they will be exposed to this type of abuse. This characteristic also makes it advisable to take extra care when setting stones which have thin girdles.

Hardness: The hardness of Oregon Sunstone varies, and various stones have tested from 6.5 - 7.0 on the Mohs scale. This makes it more durable that Andesine and many other types of Feldspar gems, but care should still be taken against hard blows, and against rubbing against harder gemstones such as Sapphire, Ruby or Diamonds (all of which can cause scratching).

Cleaning: Clean Oregon Sunstone using warm, soapy water. Avoid abrasives, chemicals, ultra-sonic cleaners and heat, as all of these can harm or even shatter Oregon Sunstones.

Other subjects on which I've written recent Guides...
Other Gemstones
Coin Collecting

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