The Adularescence

What is the adularescence of a gemstone?

Definition

Adularescence is an optical phenomenon observed particularly in moonstone, characterized by a milky sheen, often bluish-white, that appears to float on the gem’s surface. It is caused by the diffusion of light within the stone, resulting from interference created by the irregular alternation of layers of two types of feldspar: albite and orthoclase.

Adularescence of a 0.68-carat moonstone, Madagascar, © Arvernes-Gemmes
Adularescence of a 0.68-carat moonstone, Madagascar, © Arvernes-Gemmes