When a some sort of small object or irritant becomes embedded in the tissue of an oyster or mollusk a pearl is formed. In response to the irritant, the mollusk secretes nacre, a combination of crystalline and organic substances. The nacre builds up in layers and surrounds the irritant, eventually forming a pearl.
Natural pearls are very rare and are formed in nature by a parasite or a piece of food lodging itself in the gonad or mantle tissue of a host oyster. Cultured pearls are started by humans inserting a foreign object into the tissue of an oyster or mollusk. The same natural process of creating a pearl occurs in natural pearls and cultured pearls but in natural pearls the process is begun by chance and cultured pearls are started intentionally.
Japanese researchers made a lot of discoveries in the late 19th and early 20th centuries that ended up resulting in the production of the modern-day cultured pearls that we purchase today. Kokichi Mikimoto made a remarkable discovery that created a specific technique for creating a round pearl within the tissue of an oyster.
Kokichi Mikimoto's discovery changed the pearl industry forever. This discovery gave pearl farmers the ability to cultivate large amounts of high-quality pearls in a reliable manner. Unlike the natural pearls that have a wide variety of shapes, sizes, and characteristics, the cultured pearls can be designed from the beginning to be round and flawless for the most part. The oysters could be monitored during the several years required for each pearl to become fully formed, thus better insuring their health and survival. The pearls could be grown by the tens of thousands, therefore bringing their cost down to a point where pearls became accessible to large numbers of people around the world.
It is incredible how far the pearl industry has came over time. Cultured pearls can often be distinguished from natural pearls through the use of x-rays, which reveals the inner nucleus of the pearl.
