Adularescence

1. A milky white to bluish sheen in gemstones. CMD
2. The changeable white to pale bluish luster of an adularia cut cabochon. Webster 3rd
3. A floating, billowy, white or bluish light, seen in certain directions as a gemstone (usually adularia) is turned, caused by diffused reflection of light from parallel intergrowths of another feldspar of slightly different refractive index from the main mass. Syn: schiller
   Source: Dictionary of Mining, Mineral, and Related Terms