(Cultured Pearl, Platinum and Diamond Necklace, Circa 1940; image courtesy of Sotheby’s.)
Natural pearls, as the name suggests, are formed without any influence from mankind, whatsoever. They form in the bodies of shellfish also known as mollusks.
Cultured pearls, on the other hand, are, yet again as the name suggests, grown in a special preparation and specifically for the purpose of collecting pearls then used in the process of jewellery making.
There are four kinds of cultured pearls:
Most often cultivated in Tahiti and other islands of French Polynesia which is where the name comes from. These pearls are an average of 9.5 mm with shapes that range from spherical to oval to baroque; they come in colours of Black to brown with bluish green hues and overtones between green, blue and pink. Tahitian pearls have a fair amount of lustre and the surface quality ranges from spotted to clean and the nacre quality is quite decent as well.
These pearls are cultivated in saltwater bodies in Japan and China with an average size of 6 to 8 mm in near-round and round spheres. Akoya pearls are mostly white or creamy with yellowish pinkish hues in overtones of pink or green. More than acceptable lustre accompanied by surfaces that aren’t too marred but fairly clean with a chalky to acceptable nacre.
(Two Cultured Pearl and Diamond Necklace and Pair of Matching Earrings; image courtesy of Sotheby’s.)
South Sea Pearls:
These pearls are cultivated in the regions surrounding the Philippines, the land down under; Australia and Indonesia. The orb-like pearls are of an average size nearing 13 mm and the shape ranges from round to baroque with colours that are rather sombre in elegant tones of white, cream and silver with yellowish, orangey bluish tones and overtones of pinks, greens and blues. The lustre of these gems is more than acceptable to them, a healthy amount of sparkle and reflection, a mostly clean surface with an acceptable nacre quality.
Chinese Freshwater Pearls:
These freshwater pearls are often cultured in freshwater ponds or lakes, in the USA and China for the most part. The typical size of such a cultured gem is between 4 to 14 mm in a range that again falls anywhere between round and sem0i-round to baroque. The colours these come in are white or cream with colourful hues that are yellow, orange, pink and purple. The overtone adds a rather lovely mix to the pearl with colours of pink, blue and green of which the orient plays a part as well. The lustre is nothing short of admirable with a surface that is mostly clean or in some cases moderately / slightly spotted with a yet again acceptable nacre quality.
The process of culturing pearls as such deals with a trained expert extracting mantle tissue from a mollusc and inserting a small part of the tissue along with a shell bead into the gonad or mantle of another host mollusc. Over time the tissue grows and a sac is formed around the bead onto with nacre is secreted and eventually, voila; a pearl forms!