Where do pearls come from?

Pearls are made by oysters. Their shells are lined with a hard, shiny material called mother-of-pearl. Sometimes, a grain of sand or grit gets inside an oyster's shell. The oyster then covers this with mother-of-pearl to stop the grain from irritating it.

The oyster keeps putting layers of mother-of-pearl over the grain. After many months, it will form a pearl. Natural pearls are very rare and expensive. Artificial pearls are made by putting glass beads inside oysters. The oysters cover the beads with mother-of-pearl.