Moonstone: Moonstone is the trade name of the variety feldspar belonging to the orthoclase mineral species. Feldspar is a very common mineral and takes up 60% of the earth’s crust. However, not all feldspar are ‘moonstones’. In order to be called a moonstone, adularescence must be present. Adularescence is the name given to the internal lunar-like glow moonstones exhibit. The most prized moonstones are clean, clear with intense blue or ‘rainbow’ adularescence. Moonstones can also have base colors of white, peach/pink, gray, brown, green, and yellow.
(image via Siam Gem Palace)