Pearl Information

Pearl Definition

Although the traditional source of pearls has been oysters which live in saltwater, mollusks which live in freshwater lakes and rivers can also produce pearls. China has harvested freshwater pearls for many a millennia. The first record mentioning pearls in China was from 2206 BC. The United States was also a major source of freshwater pearls from the discovery of the New World up through the 19th century, when over-harvesting and increasing pollution significantly reduced the number of available pearl-forming mussels.

Freshwater pearls are often somewhat less lustrous than their saltwater counterparts. However, they appear in a wide variety of shapes and colors, and they tend to be less expensive than saltwater pearls, making them quite popular. Freshwater pearls are also quite durable, resisting chipping, wear, and degeneration.

Freshwater pearls differ from other cultured pearls in that they are not bead-nucleated. Freshwater mollusks are nucleated by creating a small incision in the fleshy mantle tissue and inserting a piece of mantle tissue from another oyster. This process may be completed 25 times on either side of the mantle, producing up to 50 pearls at a time. The mollusks are then returned to their freshwater environment where they are tended for 2-6 years. The resulting pearls are of solid nacre, but without a bead nucleus to guide the growth process, the pearls are rarely round.

In recent years the Chinese have been able to take the art of culturing freshwater pearls to new levels. In the last decade the quality of pearls produced have become so high that many pearls in the top percentage of a harvest are nearly indistinguishable of their saltwater relatives. Gone are the rice-shape seed pearls as they are now being replaced with round, lustrous pearls of sizes as large as 16mm, mimicking large South Sea pearls. This has created a renewed interest in freshwater pearls as an affordable alternative to the higher priced saltwater.

The Japanese have a distinguished history of culturing freshwater pearls as well. Lake Biwa was once world renowned for producing high-quality freshwater pearls. However, in the mid 1970's pearl farming all but came to a halt due to pollution in this lake that was once synonymous with freshwater pearls. Today the Japanese are trying once again to farm freshwater pearls in Lake Kasumigaura, utilizing a bead-nucleated hybrid mussel ( Hyriopsis Schlegeli anadonata/plicata hybrid mussels). The resulting pearls have been quite large and unique. But due to the high prices of such pearls the market remains a niche for collectors.

Pearl Color

An inportant value factor to consider when grading pearlsis the color - both overtone and body color.

Pearls come in a wide variety of colors, ranging from white all the way to black. Here again (as with many of the characteristics of pearls), the fact that the pearl is an organic gemstone, formed within a living creature, contributes to the myriad unique ways in which its coloration can develop.

The natural color of a pearl results from a combination of several factors:

The pearl's bodycolor is its main color. This can be white, silver, cream-colored, gold, green, blue, or even black. The bodycolor is determined by the type of oyster or mollusk that produces the pearl (certain types of oysters generally produce pearls of certain colors), as well as the conditions of the water, and sometimes the type of nucleus which is implanted to stimulate the pearl's creation.
Overtones are translucent colors which sometimes appear over top of the pearl's main bodycolor. These overtones tend to alter the bodycolor somewhat, as well as adding depth and glow. A pearl may be white with rose overtones, for example. Some pearls have no overtones at all.
The term orient refers to the shimmering, iridescent colors which appear to move and glitter when the pearl is turned. This phenomenon is caused by the way in which light is reflected through the various thin layers of nacre which make up the pearl.

Pearl Shapes

Because pearls are natural organic substances, they can occur in a wide variety of shapes, many of which are quite unique and interesting. The round pearls you most commonly see are by no means the only shape in which pearls are found!

Indeed, perfectly round pearls are actually quite rare. This is because the eventual shape of the pearl is determined by a number of highly variable factors which occur inside the oyster as the pearl is developing. For example, the pearl often assumes the same shape as its nucleus (the irritant which was placed inside the oyster to initiate the formation of the pearl). If the nucleus is not perfectly round, the resulting pearl is likely to reflect this irregularity. In addition, the pearl's positioning within the oyster also plays a role in determining its shape. If the pearl develops against the shell, for example, it will become more flattened on that side.

Pearl experts generally divide pearl shapes into three broad categories, based on their overall characteristics:

Spherical shapes are perfectly round or nearly round. They are the "classic" pearl shape that is most familiar.
Symmetrical shapes are are balanced and regular. If you sliced this pearl in half, each half would be a mirror-image of the other half.
Baroque shapes are irregular or abstract. They are non-symmetrical in nature.

Within these three broad categories, pearls can be classified into seven basic shapes:

Round: Round pearls are perfectly spherical -- the shape most people think of when they think of a pearl. Because of their relative rarity and "classic" nature, they are highly desirable. Round pearls fall into the spherical category.
Near-round: These pearls are not perfectly round. Instead, they are slightly flattened or elongated, rather than being a perfect sphere. Nonetheless, they are so nearly perfect that they, too, are classified as spherical.
Oval: These pearls are shaped like an oval -- narrower at the ends than they are in the center. Ovals are categorized as a symmetrical shape.
Button: Button pearls are flattened to some degree, making them resemble a button or perhaps a disk rather than a perfect sphere. These pearls are often used in earrings, where the flattened side can be attached to the setting. Buttons are also categorized as symmetrical.
Drop: Drop pearls are pear- or teardrop-shaped. The drop can either be "long" or "short," depending on its proportions. These pearls make attractive earrings or pendants. This is also a symmetrical shape.
Semi-baroque: These pearls are slightly irregular in their shape. For example, a pearl which might otherwise be considered an oval, button, or drop pearl, but which is not symmetrical in nature, would be considered semi-baroque. Semi-baroque pearls fall into the baroque category of shapes.
Baroque: This is a pearl which is both non-symmetrical and irregular in shape. The baroque pearl can be purely abstract in its shape, or it can resemble a cross, stick, or some other shape. Baroque pearls fall into the baroque category.

Within these basic categories and definitions, there can be many variations. Some pearls, for example, develop with one or more grooves or rings encircling them. These pearls are known as ringed or circled. This adjective can be attached to the primary shape in order to more fully describe the pearl, such as "circled round" or "ringed oval."

The shape of the pearl is one of several factors which goes into determining its quality, and therefore also its value. In general, round and near-round pearls are the most valuable, because of their rarity. Symmetrical shapes are generally considered to be more desirable than baroque shapes. Baroques, however, can be extremely unique, thus increasing their desirability more than might be expected based on their shape alone.