The only gemstone made by a living organism. When a foreign body enters the shell, the mollusc coats it in nacre. Thin layers of calcium carbonate and conchiolin—an organic protein—accumulate thousands of times over to form a single pearl.

Before Mikimoto Kōkichi produced the first cultured pearl in 1893, natural pearls required diving and the opening of thousands of shells for the chance of finding one. The invention of cultivation rewrote the history of pearls entirely.

Not a mineral. Organic matter. Made by a living thing, changing with time, eventually deteriorating. Impermanence is the nature of this material.