Sunstone’s phenomenal varieties show a distinct and lively glitter called aventurescence.
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.
Sunstone is a member of the feldspar group of minerals.
Sunstone can have a sparkly, metallic-looking luster caused by flat, reflective inclusions.
Oregon sunstone is a transparent feldspar with glittery copper inclusions.
- Mineral: Feldspar
- Chemical composition:
- Orthoclase – KAlSi3O8
- Oligoclase and labradorite – solid solution between NaAlSi3O8 and CaAl2Si2O8
- Color: Yellow, green, red, red-brown, colorless
- Refractive Index:
- Orthoclase sunstone – 1.518 to 1.526
- Oligoclase sunstone – 1.537 to 1.547
- Labradorite sunstone – 1.559 to 1.568
- Orthoclase – 0.005 to 0.008
- Oligoclase and labradorite – 0.007 to 0.010
- Specific gravity:
- Orthoclase – 2.58
- Oligoclase – 2.65
- Labradorite – 2.70
- Mohs hardness: 6.0 – 7.2
The following factors combine to determine a sunstone’s value.
The most in-demand sunstone colors are deep red – like this gem – deep green, and intense bicolors.
Small inclusions provide a reddish or golden sheen; larger inclusions create glittering reflections.
Creative cuts and calibrated gems alike are designed to highlight the gem’s glowing colors.
Sunstone is available in a range of sizes, but large carved gems like this Oregon beauty are rare.