Adularescence is an optical phenomena often called the “moonstone” effect. The phenomenon is applied to feldspar, usually orthoclase that, when cut as a cabochon, exhibits a floating, billowy bluish or white light as the stone is turned. Referred to as schiller by mineralogists.

Victorian Moonstone Fringe Necklace.

Victorian Moonstone Fringe Necklace with Adularescence.