Perhaps the best-loved gems of all time, pearls—both natural and modern cultured pearls—occur in a wide variety of colours. The most familiar colours are white and cream (a light yellowish brown). Black, grey and silver are also fairly common, but the palette of pearl colours extends to every hue. The main colour, or bodycolour, is often modified by additional colours called overtones, which are typically pink (sometimes called rosé), green, purple or blue. Some pearls also show the iridescent phenomenon known as orient.
This newly opened akoya pearl oyster reveals the cultured pearl that grew inside its gonad. This oyster’s scientific name is pinctada fucata (martensii).
Cultured pearls are popular for bead necklaces and bracelets, or mounted in solitaires, pairs or clusters for use in earrings, rings and pendants. Larger pearls with unusual shapes are popular with creative jewellery designers.
This multicoloured necklace combines the beauty of Tahitian and South Sea cultured pearls. The scientific names of the oysters that produced them are, respectively, Pinctada margaritifera and Pinctada maxima. - Courtesy Frank Mastoloni & Sons, Inc.
Pearl—natural or cultured—is a birthstone for June, together with alexandrite and moonstone.
Natural pearls form in the bodies, or mantle tissue, of certain molluscs, usually around a microscopic irritant, and always without human help of any kind.
The growth of cultured pearls requires human intervention and care. Today, most of the molluscs used in the culturing process are raised specifically for that purpose, although some wild molluscs are still collected and used.
This group of cultured pearls displays some of the exotic colours pearls can exhibit. - Blaire Beavers, courtesy Takayas Mizuno
To begin the process, a skilled technician takes mantle tissue from a sacrificed mollusc of the same species and inserts a shell bead along with a small piece of mantle tissue into a host mollusc’s gonad, or several pieces of mantle tissue without beads into a host mollusc’s mantle. If a bead is used, the mantle tissue grows and forms a sac around it and secretes nacre inward and onto the bead to eventually form a cultured pearl. If no bead is used, nacre forms around the individual implanted mantle tissue pieces. Workers tend the molluscs until the cultured pearls are harvested.
There are four major types of cultured whole pearls:
Akoya—This type is most familiar to many jewellery customers. Japan and China both produce saltwater akoya cultured pearls.
South Sea—Australia, Indonesia and the Philippines are leading sources of these saltwater cultured pearls.
Tahitian—Cultivated primarily around the islands of French Polynesia (the most familiar of these is Tahiti), these saltwater cultured pearls usually range from white to black.
Freshwater—These are usually cultured in freshwater lakes and ponds. They’re produced in a wide range of sizes, shapes and colours. China and the US are the leading sources.
Cultured pearls from Australia, Indonesia, the Philippines and Myanmar are grown in the Pinctada Maxima mollusc. This shell one is called gold-lipped because of the colour of the outer rim of its mother-of-pearl layer.
The black-lipped mollusc can produce a variety of cultured pearl colours. The colour of the mother-of-pearl layer is often related to the colour of the resulting cultured pearl’s nacre. - Courtesy A & Z Pearls and Tasaki Shinju Co
The images in this chart represent typical ranges of size, shape, colour, lustre, surface and nacre quality of akoya cultured pearls.
The images in this chart represent typical ranges of size, shape, colour, lustre, surface and nacre quality of South Sea cultured pearls.
The images in this chart represent typical ranges of size, shape, colour, lustre, surface and nacre quality of Tahitian cultured pearls.
The images in this chart represent typical ranges of size, shape, colour, lustre, surface and nacre quality of Chinese freshwater cultured pearls cultured pearls.