Adularescence is an optical phenomenon that is produced in gemstones like moonstone. It is best described as a milky, bluish luster or glow originating from below the surface of the gemstone. The luster, appearing to move as the gemstone is turned or as the light source is moved, gives the impression of moonlight floating on water. It is most typically produced in adularia, an orthoclase. This photograph shows adularescence in a moonstone cabochon from Minas Gerais, Brazil.
Photographer: Didier Descouens
