The most famous types of cultured sea pearls are:
- Akoya Pearl
- South Sea pearls
- Tahitian pearl.
The colour of the pearl depends on the type of oyster that produced it, and therefore on the "place of residence" of that particular oyster.
The oyster Pinctada martensii, which lives off the coast of Japan and China, produces pearls ranging in size from 2 to 10 mm. The shape varies from round to irregular. Pearls are usually white with creamy, greyish, bluish, golden-green, silvery colours, as well as pink with various nuances. They are greatly valued for their richness of colour and extraordinary brilliance.
South Sea pearls
White and golden pearls larger than 10 mm in diameter are born in the largest Pinctada maxima oysters in the warm waters of the South Seas off the coast of Australia, Indonesia and Thailand. These pearls are known for their exceptional size and splendid colours.
The oyster Pinctada margaritifera lives off the coast of Tahiti and French Polynesia and produces naturally occurring black pearls. The pearls range in size from 8.5 to 20 mm and can come in blue, grey, green and purple hues. They are highly prized for their beautiful colour nuances and the time they take to grow.
These pearls are obtained by introducing a piece of the mollusk's mantle rather than the hard core. The tissue dissolves and the pearl turns into a thick layer of nacre. Freshwater pearls are very easy to recognize because of their fancy shape, sometimes elongated, resembling grains of rice or grapes. There are lavender, peach, tangerine and green-blue shades. It is used very widely in jewellery as an inexpensive alternative for a wide stratum of less wealthy customers.
The uniqueness of pearls lies not only in their colour and origin, but also in the shape that nature endows them with. In Japan, the usual round shape is called "happo korogashi. Fans of this unique "living" stone know that there are many other shapes, such as hemispherical "mabe" pearls and three-quarter pearls often used in various brooches. According to the degree of the so-called deformation, jewelers who work with pearls distinguish between oval, drop and baroque pearls. However, this does not mean that such pearls are valued less, as some of them, due to their fancy shape, are quite highly valued. Pearls that have a concave or curved surface are called the "monster pearls".
Often, nature itself joins two pearls as they grow; therefore, such pearls are called twins. Among the great number of pearls one can sometimes find those resembling telephone tubes, cat heads, buttons, wolfs, mushrooms, hearts, snails, etc. Being a natural phenomenon, they are quite highly valued.