Pearls are organic gems, created when an oyster covers a foreign object with beautiful layers of nacre. Long ago, pearls were important financial assets, comparable in price to real estate, as thousands of oysters had to be searched for just one pearl. They were rare because they were created only by chance.
Today pearls are cultured by Man. Shell beads are placed inside an oyster and the oyster is returned to the water. When the pearls are later harvested, the oyster has covered the bead with layers of nacre. Most cultured pearls are produced in Japan. In the warmer waters of the South Pacific, larger oysters produce South Sea cultured pearls and Tahitian black cultured pearls, which are larger in size. Freshwater pearls are cultured in mussels, mostly in China.
The quality of pearls is judged by the orient, which is the soft iridescence caused by the refraction of light by the layers of nacre, and lustre, the reflectivity and shine of the surface. Fine pearls do not have any flaws or spots in the nacre: it has an even, smooth texture. Other factors which affect value are the regularity of the shape, size, and colour: rose tints are the most favoured.
The natural range of colours in freshwater pearls is from white to tan to gray, depending primarily on the species that is used in production. Enhancements are so common that unless it is specifically stated by the seller, you should assume a pearl has been at least bleached to remove dark spots of conchiolin that show through the nacre. More dramatic techniques, such as dying or irradiation, produce pearls with exotic colours such as green, rose and lavender.
Although pearls are delicate, they have been successfully used in jewellery for thousands of years. As they are sensitive to heat, chemicals and abrasion, they should be stored in a cloth bag or their own box away from contact with other materials. They should be protected from chemicals such as hairspray and perfume. Wiping them with a damp cloth after wearing and occasional cleaning in mild soapy water is all that's required. Under no circumstances should they be placed in an ultrasonic or steam cleaner. Jewellery settings in rings and bracelets should be protective, or if not, (as in many pearl rings,) the piece should be considered for occasional use only, rather than daily wear.
Faux pearls have been around for a long time and can consist of a variety of materials such as glass, plastic or shell with various surface treatments meant to simulate the pearls lustre. A rule of thumb when testing a suspect pearl is to rub it across the surface of your teeth. Real pearls will feel slightly gritty, most imitations will feel smooth.
