Overview
About Sunstone
Sunstone is a member of the feldspar group. Both the orthoclase and the plagioclase feldspar species boast a sunstone variety. Other feldspar group gems include moonstone, non-phenomenal orthoclase, phenomenal and non-phenomenal labradorite, and amazonite. Sunstone from Oregon is gaining attention as a natural and untreated product of the United States.
Feldspar
Sunstone is a member of the feldspar group of minerals.
Aventurescence
Sunstone can have a sparkly, metallic-looking luster caused by flat, reflective inclusions.
Oregon
Oregon sunstone is a transparent feldspar with glittery copper inclusions.
Facts
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Mineral:
Feldspar
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Chemical composition:
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Orthoclase - KAlSi3O8
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Oligoclase and labradorite - solid solution between NaAlSi3O8 and CaAl2Si2O8
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Color:
Yellow, green, red, red-brown, colorless
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Refractive Index:
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Orthoclase sunstone - 1.518 to 1.526
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Oligoclase sunstone - 1.537 to 1.547
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Labradorite sunstone - 1.559 to 1.568
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Birefringence:
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Orthoclase - 0.005 to 0.008
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Oligoclase and labradorite - 0.007 to 0.010
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Specific gravity:
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Orthoclase - 2.58
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Oligoclase - 2.65
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Labradorite - 2.70
- Mohs hardness: 6.0 – 7.2
Treatments
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.
Learn MoreSynthetics
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.
Learn MoreImitations
Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.
Learn More
Why We Love This Gemstone
Glittery
Reflective inclusions in sunstone’s phenomenal varieties cause a distinct and lively glitter called aventurescence.
Natural
Oregon sunstone’s colors don’t result from treatment. The gem’s all natural and it’s mined in the United States.
“Spinel red”
Red-colored Oregon sunstone is often marketed to consumers as “spinel red.” Its vivid hue rivals spinel and even ruby.
Quality Factors
The following factors combine to determine a sunstone’s value.
Color
The most in-demand sunstone colors are deep red – like this gem – deep green, and intense bicolors.
Clarity
Small inclusions provide a reddish or golden sheen; larger inclusions create glittering reflections.
Cut
Creative cuts and calibrated gems alike are designed to highlight the gem’s glowing colors.
Carat Weight
Sunstone is available in a range of sizes, but large carved gems like this Oregon beauty are rare.
Sunstone Quality Factors: The Comprehensive Guide
Research
Explore sources, gemological research, and the role of gems in history.
Special Colors and Optical Effects of Oregon Sunstone: Absorption, Scattering, Pleochroism, and Color Zoning
Shiyun Jin, Aaron C. Palke, Nathan D. Renfro, and Ziyin Sun , Nov 3, 2023 Read Article
Fluorescence Characteristics of Two Copper-Diffused Plagioclase Feldspars: Labradorite and Andesine
Qingchao Zhou, Chengsi Wang, and Andy H. Shen , Jan 25, 2023 Read ArticleRecommended Reading
Feldspar Mineralogy
Ribbe, P. H
