Cultured Pearls

You can't discuss the history of pearl cultivation without referencing Mikimoto Kokichi or "Mikimoto" as he is most commonly known (Kokichi is the family name). Although several other individuals are also credited with the invention of pearl cultivation, Mikimoto is the most famous.

He was born in 1858 the son of a noodle maker in Toba, Shima Province. As a boy, he would watch the pearl divers unloading their findings on the shore. This led to his love affair with the shiny, round gems.

In 1888, Mikimoto obtained a loan to start a pearl farm; however, because of over-harvesting, pearls around the shores of his hometown began to disappear. Mikimoto decided to take matters into his own hands by experimenting with ways to seed oysters by hand. After a string of failures, he finally succeeded in producing mabes, or semi-circular (half) pearls.

Meanwhile, in Australia, an expatriate British marine biologist William Saville-Kent had discovered how to create round pearls by inserting a piece of oyster epithelial membrane (the lip of mantle tissue) with a nucleus of shell or metal, into an oyster's body. Saville-Kent shared his method with Japanese government biologist Tokishi Nishikawa and a carpenter, Tatsuhei Mise.

Mikimoto eventually found a way to culture spherical pearls; however Nishikawa and Mise already had the patent. Mikimoto proposed a deal to buy it and they agreed. The patent, along with Mikimoto's hard work and keen interest in research, helped his business to expand rapidly.

In 1899, Mikimoto opened the world's first store specializing in pearl jewelry in Tokyo's fashionable Ginza district. But he was now faced with new challenges, most notably allegations that cultured pearls were imitation despite scientific reports to the contrary. Mikimoto constantly sought opportunities to refute these allegations and promote his pearls. One of his more famous publicity stunts was to cover a replica of the Liberty Bell with pearls during the 1926 Philadelphia World Exposition.

By 1935, Mikimoto's pearl empire had grown to international proportions. Newly opened stores in London, Paris, New York, Chicago, Boston, Los Angeles, San Francisco, Shanghai and Bombay made Mikimoto one of the first Japanese brands to attain an international presence and recognition. At their peak, his 350 pearl farms in Japan were producing 10 million cultured pearls annually.

Just before his death, Mikimoto was awarded the Order of Merit (First Class) by the Japanese government. In September,1954, he died at the age of 96. He was posthumously awarded the Grand Cordon of the Order of the Sacred Treasure, one of Japans highest honors.

Pearl cultivation is a labor of love. Exact details vary from farm-to-farm and from species- to-species. For example, oysters can be collected or bred, and the period of caring for them before they are implanted varies. Generally speaking, the implantation process is as follows:

1. The animals are cleaned and a skilled grafter performs a quick and precise "surgery" of implanting a bead nucleus made of organic material (often mother of pearl: the hard pearly inner layer of certain mollusk shells).
2. The bead nucleus is followed by a bit of mantle tissue from another mollusk. The mantle tissue contains cells that ensure the production of conchiolin and nacre. By giving the host animal a bit of familiar tissue, risk of nuclei rejection is reduced. The grafter's choice of mantle tissue contributes to the pearl's natural color.
3. After the animal is implanted with nuclei it must be carefully maintained in clean, healthy waters to avoid unnecessary disturbances.

Once an oyster is implanted, it begins to secrete calcium carbonate (nacre) that coats the bead nucleus. This pearly layer naturally develops irregularities in direct relation to thickness; therefore, it has to be kept extremely thin to appear flawless. Pearls tend to take on the color of their host mollusk. Most ocean pearl oysters have creamy, greenish, golden and yellow shells, so pearls need intense bleaching with hydrogen peroxide to achieve the desired white or white-pink colors.

Both thin nacre and harsh bleaching techniques can cause a rapid loss of luster, and sometimes the entire nacre layer, so take care when purchasing pearls. On the other hand, natural characteristics of oysters make it possible to choose durable Akoya pearls that could become heirlooms.

Cultured pearls are the "canaries" of their host waters. As animals will not prosper in polluted waters, neither will pearls grow. Tragic examples have occurred in the coastal waters off of Japan, and also in their fresh waters. Lake Biwa and Lake Kasumi Ga Ura both halted pearl production due to unclean waters. The perpetrator in both cases was tainted runoff from nearby industry.

It is the overwhelming responsibility of any pearl farmer to ensure clean water for their animals. Throughout the entire precious gem industry, pearl cultivators are the only group that acts as environmental protectors. As mountains are moved in search of gems and precious metals, and impoverished people are made to work in mines against their will, it is refreshing to know that the existence of pearls is a testament to healthy water and passionate farmers throughout the world.

Cultured saltwater pearls (i.e. Akoya pearls) are typically seeded with a bead nucleus and left to incubate for approximately 12 months. This is the point at which they reach peak roundness- beyond that they tend to take on an out-of-round or baroque shape. In cultured freshwater pearls, the bead nucleus is often bypassed and only a bit of graft tissue is implanted. The method of grafting with only the soft mantle tissue is a much easier process, and can yield dozens of pearls per one freshwater shell.

Freshwater pearl production mainly occurs in China. In recent years Chinese pearl farmers have gained remarkable skill in implanting freshwater mollusks with shell nuclei, and setting them directly into the body of the animal. This is the same process that has been used in saltwater pearl production for decades. Now, more and more, we see "bead nucleated" Chinese freshwater pearls on the market. In far lesser quantities, we also see examples of using more creative nuclei in unconventional shapes (discs, stars, animals, hearts etc.); wax and plastic; and sometimes even semi-precious stones. Cultured freshwater pearls (especially those with only tissue nuclei) are most often baroque.

As China became increasingly aggressive with pearl production, a multitude of new pearl shapes began to appear, including those that resembled Rice Krispies® cereal. The need soon arose to name these new shapes. Terms such as petals, rosebuds, and coins are often used, along with most popular, albeit misused "keshi" pearls. Regardless of the name, these unique, asymmetrical creations make for some of the most interesting pieces of jewelry.

Both saltwater and freshwater pearls can take on overtones in every color of the rainbow with many shades in between. Colors largely depend on the type of mollusk in which the pearl is grown; for example, Tahitian pearls come from black-lipped pearl oysters (Pinctada margaritifera) which secrete the dark nacre that is responsible for their extraordinary color.

"Keshi" is a Japanese term that means poppyseed. It was used to describe the small extra pearls that were found alongside cultured pearls produced on Japanese farms. As China became involved with pearl production, they searched for a market-recognized term for to describe the baroque (out-of-round) shapes that emerged, and settled on the term "keshi".

Chinese pearls are generally not "keshi". "Keshi" implies that the pearls were the result of a rejected nucleus, or were an accidental pearl found with the confines of a pearl farm. In actuality, "keshi" is simply a misused term which describes shape rather than origin. Keshi pearls are found in all pearl production. The most famous variety comes from Japanese Akoya farms; however, Tahitian and South Sea Pearl farms are also known for their beautiful "keshi" examples.