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Moonstone

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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Transparency

Fine moonstone is colourless and semitransparent to transparent.

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Feldspar

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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Tools

Overview

About Moonstone

Labradorite feldspar
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.

Adularescence

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


60%

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.


Facts

  • Mineral: Feldspar
    Chemistry

Where It's Found

map

Treatments

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

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Synthetics

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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Imitations

Any gem can be imitated – sometimes by man-made materials or by natural materials chosen by man to impersonate a particular gem.

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gem love

Why We Love This Gemstone

1
Rarity

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

2
Adularescence

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

3
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.

Colour

quality factors

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

Clarity

quality factors

Characteristic inclusions include tiny tension cracks called centipedes.

Cut

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

Research

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

Infrared Spectroscopic Study of Filled Moonstone

Li Jianjun, Weng Xiaofan, Yu Xiaoyan, Liu Xiaowei, Chen Zhenyu and Li Guihua Read more in English

Sri Lanka: The Gem Island

Peter C. Zwaan , Jun 1, 1982 Read more in English

Summer 1997 Gem News International

, Jun 1, 1997 Read more in English

Summer 2006 G&G Lab Notes

, Jun 1, 2006 Read more in English