There are five main types of pearls used in the jewellery industry and they are as follows.
Freshwater pearls are produced mainly in China today. They are grown in mussels in lakes and ponds, while other pearls are grown in oysters in saltwater. Good quality pearls come in all sizes up to 12mm. Their color can vary from white to purple. The range in colors can be either natural or enhanced.
The main difference between freshwater and saltwater pearls is that the mussels can produce up to forty pearls in just one harvest, whereas saltwater oysters can produce only one. That fact alone explains the abundance of freshwater pearls today.
Akoya pearls are also known as the classic pearl. They are cultivated in Japan and China. The oyster used is a small oyster that reaches a maximum size of 8cm. This explains the maximum pearl size of 10mm. The color is mainly white but golden and blue colors can occur. Presently, the cultivation period is very short, which results in thinner nacre.
White South Sea Pearls
White South Sea Pearls are the most expensive pearls, due to their large size (8 – 20mm), quality, rarity and difficulty to produce. These pearls are mainly produced in Australia, Indonesia and the Philippines. The oyster used in cultivation is the largest mollusk that can produce pearls. It can grow up to 35cm and also deposits a very thick nacreous coating. Most often they are white to silver in color, although at times pink, blue, and green colors are produced.
Golden South Sea Pearls
Mainly produced in the Philippines and Indonesia, the golden color of these pearls is 100% natural. They are grown in a gold-lipped oyster. It is the recessive gene of the white, silver-lipped oyster that produces the Golden South Sea pearls. Through selective breeding of these oysters, they have been able to produce colors ranging from champagne to deep gold.
Sizes range from 8 – 20mm. They tend to be very valuable due not only to their beauty and size, but also because of the complications in the farming of these pearls. Their oysters are very sensitive to the quality of the water, especially the concentration of plankton in the water.
Black Pearls (Tahitian)
Although they are produced in French Polynesia, Fiji and the Cook Islands, Tahiti is the trading center from which they are exported. The oyster responsible for the production of these pearls is the black-lipped oyster. Their sizes range from 8 – 18mm and vary in color from black to aborigine to green to gray.