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  Seeds for Cultured Pearls

cultured pearls
Cultured Pearls from oysters seeded with fresh water mussel shell.
Jake Wolf Fish Hatchery exhibit.
Zoom in on cultured pearls

A new market appeared for shells. The Japanese had discovered in 1909 that a mussel shell nucleus inserted into a pearl oyster produced a much higher quality cultured pearl than the lead beads they had been using. The size of the nucleus (not just the length of the growing period) determines the size of the finished pearl.

As World War II ended, soldiers returned with pearl jewelry from Japan. A demand was created for Japanese pearls. A revival in mussel gathering began during the 1960s when the Japanese who did not have a continuous source of mussel shell in Japan, expanded their search for shell material to use in cultured pearl production for trade with China and the United States. The Japanese bought and shipped train-car loads of Three-ridge, Pig-toe, Warty-back, and Washboard mussel shells from the Midwestern United States. A ton of shells yielded about 60 pounds of nuclei.

The process of making pearl nuclei is to cut small cubes of shell, tumble and pressure-grind them into small balls, then insert them into salt-water oysters. Within a year the oysters secrete a thin layer of nacre around the mussel shell to create a cultured pearl Go to image of fresh-water pearls . The nacre in the shell nucleus does not crack when the pearl is drilled for stringing.

This new market kept many Illinois musselers in business throughout the 1950s and 1960s digging shells for export. For example, in 1966 almost two million pounds of shells were harvested from the Wabash and White Rivers in eastern Illinois for this purpose, and shellers in Pearl, Illinois were still shipping shell to Japan in 1987.

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