Moonstone is a variety of orthoclase feldspar, which is a sodium aluminum silicate. Moonstones can occur colorless, blue-wjite, white and pale shades of apricot and peach. The rarest and most expensive moonstones will be colorless with a floating blue color or schiller that seems to hover above the stone. This phenomenon is termed adularescence and is due to a combination of orthoclase and albite feldspars, arranged in layers. Light reflected from these layers produces interference effects and causes the adularescence. If the layers are very thin, a blue schiller is seen; when they are thicker a white schiller is seen.

The most important source for moonstone is Sri Lanka. Water-worn stones are often found in the alluvial gem gravels on the southern part of the Island.

A Brief History of Moonstone

The Romans, from about 100 A.D, used moonstone in jewelry. They believed that the stone was formed from the light of the moon. Moonstone is considered a sacred stone in India, where it was believed that moonstones placed in the mouth during a full moon would allow you to correctly envision the future.