Adularescence

Adularescence in a moonstone cabochon, Minas Gerais, Brazil. The specimen's diameter is 23 mm (0.91 in).

Adularescence (/ˌædʒələˈrɛsəns/ AJ-ə-lə-RES-əns) is an optical phenomenon that is produced in gemstones like moonstone. The optical effect is similar to labradorescence and aventurescence.