Some specimens of moonstone can be cut to yield a cabochon that exhibits chatoyance (cat’s-eye moonstone) or four-ray asterism (star moonstone). When properly cut, gems that display these phenomena can be beautiful and highly desirable. An accompanying photo shows a very nice example of a transparent cat’s-eye moonstone. Another accompanying photo shows a milky white moonstone cabochon…

Moonstone occurs in a wide range of bodycolors. These include white, gray, brown, pink, orange, green, yellow and colorless. Each of these bodycolors makes a beautiful gem. The adularescence is usually a white to silvery sheen. Rarely, colorless specimens of feldspar will produce a spectacular blue adularescence. This phenomenon is often called “blue flash” or…

Moonstone is sometimes used to produce doublet cabochons. These are made by gluing a slab of quartz to a thin slice of blue flash moonstone. A cabochon is then cut from the material with the moonstone slice serving as the base of the cabochon. When these are properly cut and presented in jewelry the result…

The most important job in cutting a moonstone cabochon is orienting the rough. This requires a knowledge of how light enters and behaves within the stone. The cutter must first identify the plane of adularescence. This plane will always be a parallel to a cleavage direction of the mineral. Cleavage surfaces are then examined, looking for…

Adularescence is observed in pieces of feldspar that contain thin alternating layers of orthoclase and albite. These micron-thick layers of different composition also have different refractive indexes. Light, penetrating one layer after another, is bent, reflected and scattered at the surface of each layer. The scattered light within the stone is what causes the adularescent…

Sri Lanka is the world’s most important source of fine-quality moonstone. Moonstone is also produced in significant quantities in Brazil, Myanmar and India. Small amounts are found in many other countries around the world. Large, mechanized moonstone mines do not exist. Instead, most production is from artisinal mining. The miners prospect through stream sediments and gravels where moonstone is found,…

Moonstone serves as a birthstone for the month of June. It is one of the orignial modern birthstones established in 1912. It shares the title of June birthstone with pearls and alexandrite.

Moonstone is the popular name used for gem-quality feldspar that exhibits the phenomenon of adularescence. Adularescence is a soft glow of light that appears to float just below the surface of a polished gemstone, usually a cabochon. The name “moonstone” was given because the floating light resembles the glow of the moon through a thin cloud cover. The glow…