Pearl Akoya

The Akoya pearl oyster, Pmctada Jucata moitenm, is again smaller, measuring 8 to 10 centimetres across. It has silvery nacre inside the shell. Akoyas are used in Japan to produce their world- mous nucleated cultured pearls, and are now also being used in China and other parts of the Far East. The cultured pearls produced by these oysters vary in size fiom 2 to 10 millimetres in diameter, and are white to cream in colour. 

The first cultivation process was a system developed by the Japanese company Mikimoto, and it is still the method cuirendy used for culturing Akoya pearls. 

South Sea pearls are large, and are grown in, for example, the silver-and golden-lipped oysters, which are much larger than the Akoyas. South Sea pearls are also nucleated with mother-of-pearl beads, but only one is inserted at a time. They produce nacre faster than Akoyas and are left in the sea for two years, resulting in the thicker nacreous layer that is typical of South Sea pearls (Fig. 9.4). The oysters are suspended from off-shore floats, at a depth of 10 to 15 metres, and are tended and harvested by divers who sail out to the oyster beds on boats equipped as laboratories. 

Some spedes of oyster for example the South Sea pearl oyster, can be nudeated a second time, immediately after the first pearl has been remored, by inserting a new bead into the pearl sac already there. Akoyas can only be nudeated once. 

In the mid-1990s the Akoyas in Japan were struck by a virus that reduced cultured pearl production by 75 per cent, seriously damaging the cultured pearl industry of that country. 

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