All About Pearls
A pearl is a hard, generally spherical in shape and produced within the soft tissue of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in its minute crystalline form, this is deposited in concentric layers. Meaning each layer is formed one upon the other.
The ideal pearl is perfectly round and smooth, but there are many other shapes for example (baroque pearls), these are simply pearls that have an irregular shape.
The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, very fine, very admirable, and very valuable.
Valuable pearls do however occur in the wild, but they are very rare. Cultured or farmed pearls from pearl oysters now make up the majority of those that are currently sold. Pearls from the sea are valued more highly than freshwater pearls.