What Does Cultured Mean?
In the case of cultured pearls, the process is given a helping hand - this differentiates them from natural pearls. Rather than waiting for a foreign body to accidentally lodge within the mollusc, the cultured pearl farmer will deliberately plant a small shell fragment within it, before allowing nature to take its course. The nacre is then secreted by the mantle of the mollusc, and forms in concentric layers around the foreign particle, creating a pearl.
The vast majority of pearl jewellery today is derived from this process.
Types of Cultured Pearl
Cultured Pearls can be grown in a variety of molluscs in different parts of the world. These are the three most widely used in fine jewellery, although recently freshwater cultured pearls have also been used.
Akoya cultured pearls (Oyster: Pinctada Martensi): These come mainly from the seas around Japan and account for the vast majority of cultured pearls on the world market today. They range in size from 2.5 mm - 10 mm, in shape from round to slightly baroque, and though basically white in colour, their overtones include silver, pink, cream, blue/grey and green.
South Sea Cultured Pearls (Oyster: Pinctada Maxima): Produced by this larger oyster around the warmer South Sea coastlines, these pearls range in size from 10-15 mm. Generally, the Australian Pearls are white with a silvery tint; those from Indonesia range from pinkish-cream through to cream and gold; and those from Toumatou from light grey to jet black.
Tahitian Pearls (Oyster: Black lipped): The cultured pearls from around Tahiti and Okinawa range from 8.5 - 15 mm in size. They are a distinctive black with overtones of blue, green and violet.
Freshwater Cultured Pearls:Today these pearls are seen as an attractive and cost effective gemstone and feature both in fine jewellery, combined with precious metals and diamonds, as well as in fashion or 'costume' jewellery. They grow in a fresh-water mussel which has been implanted with a piece of mussel tissue. This later disappears, hence they are sometimes referred to as 'non-nucleated' cultured pearls. Recent years have seen a surge in production of freshwater cultured pearls, particularly from China. Produced in vast quantities from lakes and rivers, the mussels used to grow them can be re-used to produce multiple pearls in one season, thus driving down costs. Previously these pearls have been characterised by their limited size and extremely baroque shape, but advances in production techniques are producing constant improvements.