Natural pearls are those pearls which are formed in nature, more or less by chance, by a parasite or a piece of food lodging itself in the gonad or mantle tissue of a host oyster.
Cultured pearls, by contrast, are those in which humans take a helping hand. By actually inserting a foreign object into the tissue of an oyster or mollusc, pearl farmers can induce the creation of a pearl.The same natural process of pearl creation takes place.The only difference is that in the one case, the process was begun accidentally; while in the other case, it was begun intentionally.
The discoveries of Japanese researchers, especially the techniques of Kokichi Mikimoto revolutionized the pearl industry. Although some cultures had long been able to artificially stimulate freshwater molluscs into producing a type of pearl, the pearls produced in this way were generally hemispherical mabes, rather than actual round pearls. What Mikimoto discovered was a specific technique for inducing the creation of a round pearl within the tissue of an oyster.
This discovery allowed pearl farmers to cultivate large numbers of high-quality pearls, because the shape could be influenced from the start. The host oysters could be monitored and cared for during the several years required for each pearl to become fully formed, insuring their health and survival. Due to Mr. Mikimotos technique, pearls could be harvested by tens of thousands, cutting the enormous costs to a point where pearls became accessible to a large number of people from around the world.
Today, the cultured pearl industry has replaced the natural pearl industry since culturing pearls saved the risks and speculation the natural pearl industry had to rely on. Within only 100 years the beautiful pearls became available and affordable for pearl-lovers around the world. Cultured pearls can often be distinguished from natural pearls through the use of x-rays, which reveals the inner nucleus of the pearl.
Natural pearls are very hard to find.They grow randomly, when some sort of irritant, like a parasite or a piece of food, invades the shell of an oyster or mollusc. Lodged inside, the irritant invades the mantle tissue of the mollusc.The oyster, in response to the irritation, secretes nacre, a combination of organic substances and calcium carbonate, also known as mother-of-pearl.The nacre wraps itself around the foreign substance in layers. Over a period of several years, a pearl will evolve.
Not only is it difficult to find just the one in about 10.000 molluscs which produced a pearl at all, it is even more unpredictable, whether the pearl inside has attained a desired growth, shape or colour. If left in a totally natural condition, size, shape and colour are determined by a variety of factors, depending on the shape of the original irritant or whether the mollusc is living in saltwater, freshwater and the geographic region the host oyster lives in.Therefore, natural pearls of any commercial value are extremely rare. Most natural pearls are irregularly shaped and a large percentage of the discovered ones do not match the pearl-lovers expectations.
Today, natural pearls are found primarily in older pearl jewellery from estate sales, auctions or collectors items. In the past, the were the gift for Kings, Queens and emperors, owned only by the rich and famous.There are some natural pearl beds which are increasingly harvested, including beds in the Persian gulf area and freshwater natural pearl beds in the United States. Since the early 20th century, cultured pearls have supplanted natural pearls as the most common and available pearls.
In fact, cultured pearls are also natural pearls, grown inside a living organism, just the same way natural pearls develop. In contrast to the natural pearl, humans lend a helping hand. A pearl farmer intentionally induces the process by inserting a 'nucleus' into an oyster, then the oyster is returned to the sea. Formation and discovery are no longer a matter of luck.