Pearls are calcified objects made by shellfish from the very same material that they use to form their protective shells. Sand or some other foreign material literally gets under the skin of an oyster or other shellfish, and irritates its sensitive skin. In response, the creature coats the offending grain over a period of time with layers of pearly smooth calcium. The result is of luminous beauty. Oysters can also be induced to produce pearls if a grain of sand if purposely forced between the skin and shell.

Pearls are the product of both salt- and freshwater oysters; the freshwater pearl is more elongated and irregular in shape. Pearls are considered perfect if they have an equally attractive and much are much less expensive to purchase.

Most pearls available today are cultivated in specially constructed saltwater environments, where the water is warmer and more conducive to their development. In recent years, even Japanese pearls have become less available because of increasing ocean pollution. Natural pearls are virtually non-existent because of the worldwide abuse of the water by careless industrialized nations.