Gem Library

BUYER’S OVERVIEW:
Moonstone is a member of the Orthoclase Feldspar family and is considered to be a semi-precious gemstone. While limited in nature, some good size stones are available. Moonstone owes its name to its almost magical shimmer that resembles moonshine, the bluish-white light seems to hover over the stone as it moves. This phenomena is called adularescence.

Moonstone ranges from transparent to opaque and is naturally found in colors that span a range from colorless to white with adularescence in blue, white, or rainbow color. The more transparent and colorless the moonstone, the more valuable it is. Moonstone is occasionally found in green, orange, yellow to brown or gray to black.

COLOR:
Colorless to white with adularescence in blue, white, or rainbow color. Moonstone is occasionally found in green, orange, yellow to brown or gray to black.

APPEARANCE:
Transparent to opaque.

Phenomena:
Moonstone typically exhibits the phenomena of adularescence in which a bluish-white light seems to hover over the stone as it moves. This phenomena originates from the interior structure of the gemstone. Incoming light is refracted inside the stone and scattered, creating a unique play of light. A combination of orthoclase and albite arranged in layers causes the lovely sheen.

Moonstone also has been found to exhibit the phenomena of Chatoyancy (a striking three dimensional effect typically seen in tiger eye quartz) as well as Asterism, a pattern of reflected light that forms star patterns, typically seen in sapphire and rubies.

SIZE RANGE:
1 to 25 carats, cut stones up to 250 carats are known.

TYPICAL CUTTING STYLES:
Moonstone is classically cut into cabochons as an appropriate height of the stone is essential to display the desired light reflection.

POSSIBLE ENHANCEMENTS & TREATMENTS:
Moonstone is sometimes enhanced with the addition of a blue or black coating on the back of the stone to increase the adularescence. This coating can be scraped off or removed with solvents.

HARDNESS:
6 to 6½ on the Mohs scale.

BEST USE OF THE GEMSTONE:
Moonstone is fairly soft and sensitive to pressure, it should only be used in pendants, earrings and hair decorations.

CARE & CLEANING:
It is best to never expose colored gemstones to cleaning solvents or chemicals of any kind.
Common cleaning methods include:
Ultrasonic: never
Steamer: never
Warm soapy water: safe
Reaction to Chemicals: can be damaged by acids.
Reaction to Heat: abrupt temperature changes may fracture it or break it into pieces.
Stability to Light: stable after prolonged exposure to sunlight or UV light.

INTERESTING FACTS ABOUT THIS GEMSTONE:
The word Orthoclase comes from the Greek for “break straight” and indeed, Moonstone, which belongs to the Orthoclase Feldspar family, will indeed crack or cleave straight when struck or exposed to heat or pressure.

There are different types of Moonstone. Moonstone from Sri Lanka, the classical country of origin shimmers blue on an almost transparent background. Specimens from India show play of light on beige, green, orange or brown background. Moonstone cat’s eye and multi-rayed star moonstone are known, but rare.

In Arab countries, where Moonstone is considered a symbol of fertility, women often sew moonstone into their garments.

During the “Art Nouveau” period more than 100 years ago moonstone was extremely popular. The famous French master Rene Lalique and his contemporaries used it extensively to decorate their jewelry, many of which are displayed in museums and in private collections.

DESIGNATION:
Moonstone is the Birthstone for June (Jun. 22 – Jul. 22).

GEM LORE