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A ghostly sheen moves under the surface of this feldspar, like moonlight glowing in water.

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A Cabochon

The cabochon cut helps moonstone to best display its phenomenon.

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Phenomenal Beauty

Adularescence is the light that appears to billow across a gemstone.

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Fine moonstone is colorless and semitransparent to transparent.

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Moonstone is formed of two feldspar minerals, orthoclase and albite.

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Beautiful Light

Moonstone’s shimmer of light is apparent even in its rough form.

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Twinned Crystal

This twinned moonstone shows good crystal form with flat faces.

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About Moonstone

About Moonstone
Moonstone is a variety of the feldspar-group mineral orthoclase. During formation, orthoclase and albite separate into alternating layers. When light falls between these thin layers it is scattered producing the phenomenon called adularescence. Adularescence is the light that appears to billow across a gem. Other feldspar minerals can also show adularescence including labradorite and sanidine.

Moonstone Description

Moonstone History and Lore

Birthstones & Anniversaries

Moonstone is a birthstone for June, along with pearl and alexandrite.


Moonstone’s unearthly glow is caused by light scattering between microscopic layers of feldspar.


The minerals in the feldspar family make up more than half of the Earth’s rocky crust.

0.5 Microns

Feldspar layers that create moonstone’s sheen are similar to the size of a wavelength of light.


  • Mineral: Feldspar
  • Chemistry:  KAlSi3O8
  • Color: Colorless to White, Gray, Green, Peach, Brown
  • Refractive index: 1.518 to 1.526
  • Birefringence: 0.05 to 0.008
  • Specific gravity: 2.58
  • Mohs Hardness: 6.0 to 6.5


There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.

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Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.

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Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.

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Why We Love This Gemstone


Rare in top qualities, this ethereal gem derives from one of the earth's most common minerals.


Stacked layers of orthoclase and albite diffract light, creating moonstone’s adularescence.

Another Phenomena

Besides adularescence, moonstone sometimes also shows a cat’s-eye effect.

Quality Factors

An assessment of the following characteristics determines moonstone’s value.


quality factors

The finest moonstone is a gem of glassy purity with a mobile, electric blue shimmer.


quality factors

Characteristic inclusions include tiny tension cracks called centipedes.


quality factors

As it displays moonstone’s phenomena to best advantage, cabochon is the common cut.

Carat Weight

quality factors

Moonstone comes in a wide range of sizes and carat weights.

Moonstone Quality Factors: The Comprehensive Guide


Explore sources, gemological research, and the role of gems in history.

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Imitation Rainbow Moonstone Assemblage

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Infrared Study of Filled Moonstone

Infrared Spectroscopic Study of Filled Moonstone

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