Refers to special effect pigments that mimic the luster of pearl. These include 'fish silver' (also known as 'natural pearl essence'), a pigment suspension derived from fish scales, skin, or bladder. It is the oldest pearl luster pigment known. In modern times, mica is the most important substrate for pearlescent pigments. Metal oxide-coated mica pigments have been used in commercial artists' paints since 1985 and are widely accepted as retouching pigments.