Growing of Pearls
Pearls form inside oysters, mussels, and clams (molluskan bivalves) when a small object becomes trapped inside the shell of the mollusk. Contrary to popular opinion, it is not sand that finds its way inside the shell but a small piece of clay, mud, worm, small crab, or parasite. When a foreign object enters the shell, as a self defense mechanism, the mollusk attempts to isolate the foreign object by secreting nacre (also known as mother of pearl).
Throughout time, many layers of nacre are formed around the foreign object, and a beautiful pearl is born. One might say that the conception of a natural pearl is much like the birth of a child. The genetics of a child as with a pearl depends on the two entities that converge. The shape of the pearl actually depends on the shape of the foreign object that is trapped inside the mollusk, the rounder the object—the rounder the pearl. The color of a pearl on the other hand depends on the mollusk that incubates it.
Cultured pearls are real pearls. Instead of the random occurrence of an irritant becoming trapped inside the mollusk, cultured pearls are formed through human intervention, also known as perliculture. If not for the culturing of pearls, pearl jewelry might still be restricted to royalty. Women wouldn’t have the luxury of owning pearl jewelry, brides would be able to have their bridal jewelry made of pearls, and pearl necklaces would never adorn the necks of women.
The first person to actually produce a spherical pearl was the Swedish taxonomist Carl Linnaeus. When he visited a pearl fishery in Purkijaur, Sweden during an expedition, he became fascinated with the issue of pearl harvesting, and he believed that there might be another way of growing pearls without having to rely so much on “nature.” When he returned home to Uppsala, he experimented by inserting a piece of plaster paris inside a mussel shell which he left in the Fyris River. When he retrieved the pearls six years later, he was able to culture several pearls that were the size of peas. Thus, the first spherical cultured pearls were “born” in Sweden in 1740.
Today, when we think of cultured pearls, we think of the name Mikimoto. Kikichi Mikimoto revolutionized the art of perliculture, but two other men were actually responsible for patenting the method of culturing pearls—Tokichi Nishikawa and Tatsuhei Mise. Although they did not discover the technique together, they agreed to share the credit and named it the “Mise-Nishikawa” method—they patented their technique in 1907. Since Mikimoto could not patent his technique, he changed his patent application to the technique for culturing round pearls. However, Mikimoto had the vision of an entrepreneur and he eventually bought the rights from Mise and Nishikawa. Today, the word Mikimoto connotes high quality saltwater cultured pearls. Nevertheless, the technology of saltwater pearls continues to improve.
Freshwater pearls were originally cultured in Japan’s Lake Biwa, during the 1920’s, but pollution has done great damage to this industry in Japan, and today, the primary source for freshwater pearls is China.