A pearl is a hard, general spherical object produced within the soft tissue (specifically the mantle) of a living shelled mollusc. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls, drop, oval) occur.
Cultured Pearl Key Types
There are basically three different types of saltwater cultured pearls: akoya, Tahitian and South Sea. Though they share many of the same characteristics, they can look vastly different or remarkably similar. Each comes from a different kind of Oyster.
Australian South Sea Pearls : Pinctada Maxima (White lips and Gold lips Oysters are both Pinctada Maxima)
Tahitian South Sea Pearls : Black Lipped Oyster - Pinctada Margaretifira
Japanese Akoya Pearls : Pinctada Fucata
Then we have Freshwater cultured pearls of which China produces the overwhelming majority. They are produced in a wide variety of farms, anywhere from a farmer's fishpond to massive lakes with hundreds of thousands of mussels.
Freshwater Mussel : Margaritifera margaritifera
The value of pearls in jewellery is determined by a combination of the lustre, color, size, lack of surface flaw and symmetry that are appropriate for the type of pearl under consideration. Among those attributes, luster is the most important discernment of pearl quality according to jewelers. It is the measurement of both the quantity and quality of visible light that is able to reflect from the surface of a pearl through the multiple layers of deposited nacre that have formed during the creation of the gem.
Surface blemishes, or the lack thereof, play an important role in the valuation of pearls. Generally speaking, the fewer surface blemishes a pearl has, the more valuable it is. The term "blemishes" refers to any visible bumps, marks, imperfections or small indentations on the pearl's surface. These blemishes give each pearl a unique "fingerprint" of identifying factors.
Cultured Pearl Key Shapes
A pearl's shape does not affect its quality; the demand for a particular shape, however, does have a bearing on value. Pearls of perfect symmetry such as round and tear-drop shapes are particularly rare and desirable.
Asymmetrical or baroque pearls also have a unique charm at a more moderate price than rounds. Also, since cultured pearls are grown by oysters and subject to the whims of Mother Nature, it is rare to find a pearl that is perfectly round.
Cultured Pearls Key Colors
There is such a broad spectrum available when it comes to what colors pearls are available in. There are many colors that come naturally to the pearls that are cultured, as well as pearls that have had their colors enhanced through dying or other treatments. What makes up a pearls color are one of three characteristics
Body color : the overall color of the pearl, and the color that you see most.
Overtone : The color that looks almost translucent over the main body color.
Orient : An iridescent shimmer or rainbow-like color that is on a pearls surface or just below it.