DigMyGem Gem encyclopedia

Moonstone

Feldspar Family

Moonstone is a feldspar gem defined by adularescence, a soft light that seems to move beneath its surface. In classic moonstone, light scatters from alternating microscopic layers of potassium-rich and sodium-rich feldspar; material sold as rainbow moonstone is usually labradorite.

Identity

Material or variety
Orthoclase
Scientific or material identity
Feldspar
Classification
Natural mineral or mineral variety
Aliases or trade names
Hecatolite · Adularia
Composition or formula
(K,Na,Ca)(Al,Si)₄O₈
Crystal system or structure
Variable
Geological or manufacturing origin
Forms in igneous rock or volcanic material.
Mohs hardness
6 to 6.5
Specific gravity
2.55 to 2.76

Origins

Brazil · India · Madagascar · Myanmar · Sri Lanka · Tanzania · USA

Appearance & optical properties

milky white feldspar with a floating blue adularescent sheen.

History & discovery

Its name refers to the moonlike glow. Fine material was historically associated with Mt. Adular in Switzerland, which gave rise to the name adularia. René Lalique and other Art Nouveau designers prominently used moonstone around the turn of the twentieth century, making its pale moving sheen a feature of handcrafted jewelry.

Uses & care

Common uses
Moonstone is usually cut as cabochons to display its moving sheen and set in pendants, earrings, brooches, and protected rings.
Handling and cleaning
Clean only with warm soapy water. Avoid steam, ultrasonic cleaners, high heat, sudden temperature change, and hard blows, because moonstone has poor toughness and two cleavage directions.

Jewellery

7 pieces of Moonstone jewellery. Learners earn each one in DigMyGem by learning words; until then it shows as a silhouette.

  • Silhouette of Moonrise Pendant

    Moonrise Pendant

    Pendant

    A round blue-sheen moonstone hangs in a silver crescent, glowing as if it had caught the light of a night sky.

  • Silhouette of Selene Ring

    Selene Ring

    Ring

    A tall dome-like moonstone crowns a plain gold band, the glow sliding across the stone whenever the hand turns.

  • Silhouette of Tidal Crown

    Tidal Crown

    Crown

    Waves of silver carry a row of moonstones around the head, each stone lit from within like a drowned moon.

  • Silhouette of Lantern Moonstone Brooch

    Lantern Moonstone Brooch

    Brooch

    A single oval moonstone in a plain silver frame, made to pin at the collar. Its blue sheen drifts across the stone like a lantern seen through mist.

  • Silhouette of Night Moth Pendant

    Night Moth Pendant

    Pendant

    An imagined Art Nouveau pendant of the kind French goldsmiths made when moonstone came into fashion around 1900. A gold moth spreads enamelled wings over three moonstones, with a baroque pearl hanging below.

  • Silhouette of Ceylon Moon Collar

    Ceylon Moon Collar

    Necklace

    An imagined court necklace of graduated blue-sheen moonstones from Sri Lanka, where most moonstones are mined today. Diamond spacers sit between the stones, and a large oval moonstone in a diamond halo hangs at the centre.

  • Silhouette of Mosaic Egg

    Mosaic Egg

    Jewel

    A Fabergé Easter egg that Nicholas II gave to Empress Alexandra at Easter 1914, its gold and platinum lattice set with diamonds and coloured gems like petit-point embroidery. A moonstone at the top shows the year 1914 and the Empress's initials beneath it.

Sources