Sunstone’s phenomenal varieties show a distinct and lively glitter called aventurescence.

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

• 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
  
• Birefringence: 
  
• 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

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.