A few pearls of wisdom:
In early times, people thought pearls came from rain - when a raindrop fell into an oyster shell, the mollusk produced a substance that caused the drop to harden. This belief was partly right. Pearls are created by the secretions of mollusks that form around particles of sand, not raindrops. Pearls formed in this way are called blister pearls because they are usually embedded in the lining of the shell and can be cut away to make jewelry.
In the Middle Ages the Chinese discovered that if they shoot a pellet of mud or a tiny piece of twig or bone into a mollusk and return it to its bed for three years, they could "culture" or coax the production of a pearl. But it was the Japanese who made pearl culture a fine art, by thee early 20th century.
Imitation pearls have existed for centuries; many of the ones adorned the celebrated gowns of Elizabeth I, the 16th century queen of England, are fakes. These fake or "Roman" pearls were spheres of glass filled with wax and coated with fish scale essence to make them pearly.
Amelie Von Heine
The Girl with the Pearl Earring
Natalie Portman as Anne Boleyn