Moonstone Beads and Charms from Rings & Things: With its ghostly glow, this feldspar stone almost seems magical. High-quality rainbow moonstone is usually chatoyant and sometimes displays a strong cat's eye. The floating-light phenomenon and sheen of moonstone are called adularescence or schiller. The light is scattered by alternating layers of two kinds of feldspar and produces a misty luster of white, dull yellow, yellow-gray or greenish-gray. The stone's main color also comes in shades of peach and gray. Incipient cleavage cracks often are visible inside the gemstone. Rainbow moonstone is a close relative of labradorite. It can be confused with selenite gypsum, but while selenite is very soft and can be scratched with a fingernail, moonstone is relatively hard. Moonstone is the birthstone for June in Europe, and in the United States it shares that distinction with alexandrite and pearl. Moonstone will pick up the colors that you wear, making it a versatile gemstone in fashion. Find out more about moonstone in our Gemstone Index.