Hardness 6, Specific gravity 2.57, Refractive index 1.51-1.52

Moonstone is an opaque, colorless gem that serves as a substitute for pearl. Moonstones usually have a silvery-white milky sheen called adularescence. There is a band of light, within the body of a moonstone, that is an interplay of light that moves when it is turned.

Some moonstones have a bluish opalescent sheen caused by the reflection of light. Most moonstones with this opalescent sheen are mined in Sri Lanka, and they are both rarer and more expensive than other types of moonstone because their main Sri Lankan source dried up in 1988. The bluer the stone, the more costly it is. The most expensive moonstones cost about US$700 per carat. Whitish stones have little value, and the palest stones are very cheap. Such moonstones are often made into beads.

Moonstones are also found in India, Switzerland, and Myanmar (Burma). Indian moonstones are usually low quality.

Moonstone gives good concentration, mental peace and upliftment, and can help with marriage problems, depression, stomach problems, heart problems, epilepsy, and gynecological problems.

Moonstone is more effective when worn during the bright half of the lunar month; it is weakened during the dark half. Moonstone should be set in silver and worn on the ring (although some say, little) finger.