Pearls
A pearl is a calcium carbonate deposit that has collected and been formed within the soft tissue of a shelled mollusk, such as an oyster, clam or mussel. The most sought after pearls are nacreous pearls, which are produced by mollusk bivalves or clams. These come from both the sea or from freshwater lakes.
The rarity of the pearl, which is why pearls have been so valued over the centuries, has been due to the fact that fine pearls are so rarely produced in the wild, and it took the killing of many mollusks before one was found. This resulted in the creation of a method to artificially introduce an 'irritating' core or nucleus that would encourage the development of a new "cultured" pearl.
Today, buying a Natural Pearl would really cost a fortune, Hence Cultured pearls are commonly used in day to day jewellery.
Cultured pearl also shares the same chemical and physical properties compared to Natural Pearl except that of introduction of nucleus.
It is observed that the cultured pearls has shown the similar astrological effects that of a natural pearls
Where do pearls come from?
China is today the largest producer of akoya pearls, once dominated by Japan. Japan today does not produce akoya pearls smaller than 8 mm and it remains a large processor of China's akoya pearls. South Sea pearls are primarily sourced from Australia, Indonesia and the Philippines. Black pearls are found in Tahiti and are very rare.
What shapes do pearls come in?
There are eight basic pearl shapes--round, semi-round, drop, pearl, oval, button, circle, and baroque. Semi-rounds are often used in necklaces, where their lack of full roundness can be hidden, while round pearls are the most valuable as they are the rarest. Pear shaped and drop pearls are often used in earrings, pendants or the center pearl in a necklace. Baroque pearls are very random in shape and are often used individually as center pieces or in necklaces.
Natural pearls are the most valuable
Natural pearls are the most valuable as they are the rarest and produced in small quantities. Cultured pearls will generally be less expensive, as they are more available, but also can be expensive depending on their fineness. Imitation pearls are the least expensive as they are produced in large quantities and are clearly not rare.