These also appeared on the market during the 1950's and were named Queens of Pearls because of their immense beauty and size. The mollusc is extremely difficult to breed and cultivate and in some areas it is still necessary to harvest them from the open sea. The percentage loss rate is very high, around 80%, and the majority of pearls produced are not of sufficient quality to be used in jewellery.
South Sea pearls are cultivated in warmer seas and although this hastens the growth of the pearl it also encourages uneven layer deposits greatly reducing the possibility of obtaining a perfect sphere and attractive orient.
This gives rise to a higher production cost and underlies the high market value of such gems. Depending on the geographical cultivation area and breed of mollusc either black or white pearls are produced.
White pearls with silver to gold tonalities are cultivated along the coast of North Australia and the Sulu Archipelago in the Philippines. Further north in the Birmania Sea. The Gulf of Thailand and between the Indonesian Islands warmer colours are obtained which can reach the highly appreciated and sought after intensely gold pearl. The silver or gold lip oyster, Pinctada Maxima, can reach a considerable size, up to 40cms in diameter and more than 5.5kg in weight. They are easily distinguished from Akoya pearls due to their size which ranges from 9 to 20 mm or in the case of baroque pearls up to 30 mm.
Black Tahitian pearls are harder to define as they have a incredible variety of colours and tonalities from green to bronze, grey to blue to intense black with spectacular red-green iridescence. Polynesians call them "Poe Rava". It is not possible to establish a general classification as each country has its own preferences for specific colour ranges.
Thanks to Japanese production techniques introduced in the 1960's, fishermen have become cultivators of the sea. The first pearl insertion experiments were made in the mythical Bora Bora and the first pearls were harvested there in 1963. Now they are cultivated in the lagoons of the Cook Islands, the Tuamoto Archipelago and the Gambia Islands of French Polynesia.
The mollusc used is the black lip oyster, Pinctada Margaritifera. These pearls range in size from 9 to 15 mm but can exceptionally reach over 18 mm.