Types of Pearls

Akoya Pearls
White, round, lustrous gems, Akoya pearls are grown in the Pinctada fucata oyster species. These Oysters are cultivated mainly in the cool to temparate saltwaters around Japan, China, and Korea (Japan being the largest and China the second largest producer of Akoya pearls). This temperature allows the pearl to develop highly uniform mineral crystals resulting in brilliant luster. Thus, many experts believe Akoya pearls have the highest luster of all types. The Akoya shell is no bigger than the palm of a hand and only one pearl grows in the Akoya oyster. Its pearls generally grow from 2mm to 9mm, or very rarely 10mm, the average size being between 6mm and 7mm, and the cultivation period takes between eight months and two years. Most farmers wait at least one year in hopes of a larger pearl. The colors of Akoya are rose, silver/white, cream, gold and grey/blue.

South Sea Pearls 
South Sea pearls are grown in the warm, pure waters of Australia, Indonesia, the Philippines, Myanmar and Thailand in the oyster species Pinctada maxima of which there aretwo varieties, the Silver Lipped and the Gold Lipped Oysters. These pearls and their shells are the largest and the rarest grown. It takes twenty to twenty-four months to grow the pearl and there are many complications that can cause them to die. South Sea pearl sizes range from 9mm to 20 mm, the average size being 13mm, and their colors include silver, silver/pink, white, white/pink, white/gold and gold.

Tahitian Pearls
Tahitian pearls are cultured and grown in the Pinctada Margaritifera Cumingi oyster species or Black Lipped Oyster found throughout its native waters of French Polynesia. Only 1 in 10,000 of these oysters produces a pearl and because of this rarity, they cannot be mass produced. It takes 22 to 26 months for a pearl to grown and the size range from 8 – 18 millimeters (average size is 9-10mm), but there are some extremes. The largest Tahitian ever found was 25 millimeters! Tahitian pearl colours include peacock (the most popular), black/black, black/grey, silver/grey, black/rose, black/blue, black/green and aubergine.

Freshwater
Freshwater pearls grow in a mussel species Hyriopsis Schlegeli. The mussels are not rare and are mainly found in rivers, lakes and ponds in China and Japan, and also in Europe, Russia and America. They are propagated in water tanks and ponds. There are only a small number of oysters seeded with nuclei. Most pearls are obtained by simply grafting a number of mantle tissues from another mollusk. Pearl sacs then form around the mantle, which will eventually disappear. The pearl then grows up to any possible size, depending on the number of years the oyster is left in water. In this case, the pearl produced has no nucleus inside. A Freshwater mussel can produce up to 50 pearls at a time. China now produces Freshwater pearls in enormous volumes (close to 700 tons per year). It takes approximately three to four years to reach the size of 7mm. For larger pearls, the farmer has to wait even longer. After harvesting the pearls, the mussel is placed back into its environment without a new grafting and will produce pearls again in a few years. Freshwater pearls have an endless variety of shapes, sizes and colours.

Keishi Pearls
The word 'Keshi' means 'poppy seed' in Japanese and these pearls are also sometimes referred to as seed pearls. There is considerable controversy as to the classification of whether Keshi pearls are natural pearls or cultured pearls. It is impossible to determine the difference in the laboratory. As a basic rule, if the oyster has been seeded by human intervention and an additional pearl is created through the provocation and is therefore called a “Keshi” pearl and is 100% nacre. They are generally small in size and their shapes vary widely. Keshi come in a wide variety of colours and tend to have a high lustre. Most common today are the South Sea and Tahitian Keshi pearls. Biwa freshwater pearls were cultivated in Lake Biwa in Japan from 1914 to the mid 1970's. Biwa was one of the first freshwater culturing sites and pearls from this area were noted for their high quality. However, production has now stopped due to pollution problems, and also because of competition from cheap Chinese production. The Chinese first produced a rice-shaped inferior quality, then step by step improved production to create better quality and smoother surfaces. Cost of labour is very low in China and this put the Biwa producers out of business.