The clarity ranges from transparent to translucent. The best moonstone has a blue sheen, perfect clarity, and a colorless body color. Sometimes moonstone will have an eye as well as a sheen. Another related feldspar variety is known as rainbow moonstone. In this variety of labradorite feldspar, the sheen is a variety of rainbow hues.
Fine moonstone is quite rare and becoming rarer.
It is mined in Sri Lanka and Southen India. The rainbow variety can also be found in Madagascar. Moonstones are usually cut in a smooth-domed cabochon shape to maximize the effect. Moonstone beads also display the sheen very well and are simply stunning against a black dress.