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.
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.
Feldspar layers that create moonstone’s sheen are similar to the size of a wavelength of light.
Colorless to White, Gray, Green, Peach, Brown
1.518 to 1.526
0.05 to 0.008
- Mohs Hardness: 6.0 to 6.5
Where It's Found
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.Learn More
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.Learn More
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
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.
Besides adularescence, moonstone sometimes also shows a cat’s-eye effect.
An assessment of the following characteristics determines moonstone’s value.
The finest moonstone is a gem of glassy purity with a mobile, electric blue shimmer.
Characteristic inclusions include tiny tension cracks called centipedes.
As it displays moonstone’s phenomena to best advantage, cabochon is the common cut.
Moonstone comes in a wide range of sizes and carat weights.
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