The New Student's Reference Work/Pearl

Pearl, one of the gems found in certain sea and fresh-water shells. Shells generally are lined by the animals inhabiting them with a material which gives them a smooth surface. It is laid in thin, partly transparent plates, which produce a beautiful play of colors. This lining is called mother-of-pearl or nacre. On opening the shells, there are sometimes found rounded portions of this nacre, which have been formed by throwing layers of this lining material around a grain of sand or a minute vegetable or animal growth. These are the pearls used in trade and worn as ornaments. They vary greatly in size, those about as large as a pea being the best. The largest one known is two inches long and four around. The smallest are called seed-pearls. The value depends upon size, shape, color and freedom from imperfections. The round ones are the best, the button-shaped next and the drop or pear-shaped least. Pearls, when perfectly round and of extraordinary beauty, sell for large sums; the single pearl which Cleopatra is said to have dissolved and swallowed was valued at over $400,000. The finest pearls are found close to the lips of the shell or in the soft part of the oyster near the hinge. The largest pearl fishery in America is that of Lower California, from which come the largest and finest black pearls in the market. The most famous pearls are from the east, especially from the Persian Gulf and from Ceylon. In Ceylon fishing lasts four to six weeks. Each boat has a crew of 13 men and 10 divers, five of whom rest while the other five are diving. The work has to be done very rapidly, as the best divers cannot stay longer than 80 seconds in the water. When a boatload of oysters has been obtained, the cargo is landed and piled on the shore to rot, so that the pearls can be easily found. When washing out the dead animals, a close watch is kept for loose pearls, which are always the finest, while those attached to the shells are removed by pincers or a hammer. In 1889 in 22 days 50 divers brought up 11,000,000 oysters. River-pearls are found in freshwater shells in Scotland, Wales, Ireland, Russia, Germany, Canada, the United States and China. The chief river-pearl fisheries in the United States are in the streams of the Mississippi Valley; in Wisconsin, Iowa, Kentucky, Ohio and Arkansas. The lining of the shells, mother-of-pearl, is used largely in making buttons, knife and fork handles and inlaid work on furniture. See Gems and Precious Stones of North America by Kunz and Pearls and Pearling Life by Streeter.

Courtesy Chicago Academy of Sciences

SHOWING TOOLS AND STEPS IN MANUFACTURE OF PEARL BUTTONS FROM CLAM SHELLS