Pearloid

Pearloid is a plastic that is intended to resemble mother of pearl. It is commonly used in making musical instruments, especially for pickguards, electric guitars, and accordions.
Production.
Pearloid is produced by swirling together chunks of celluloid in a solvent, then curing. It is sliced and bonded to other materials such as wood, to give the mother of pearl effect.
Use.
Pearloid is used in any context where genuine mother of pearl or abalone might be used, as it is much cheaper and doesn't deplete the supply of the natural material. Gibson uses it as a substitute for the mother of pearl inlays in the fretboards on most of their guitars. Various colored versions are often used on items intended to have a retro appearance. Pearloid is sometimes referred to, colloquially as "mother of toilet seat."