Breeding of Pearls

Pearls are one of the most beautiful creations of nature, commonly used as an element of women's jewelry. However, not everyone is aware of the fact that the process of obtaining pearls for industrial purposes is now largely controlled by mankind.

Pearls are a product of mollusks - especially sea mollusks, belonging to the family of pearl mussels. They provide natural protection from irritation by foreign bodies (e.g. the ubiquitous sand grains) penetrating the soft mantle inside the shell. Around the foreign body, concentrically arranged layers of mother-of-pearl composed mainly of aragonite are formed, gradually increasing until they reach the form of a full pearl. In cultured pearls, the introduction of a foreign body irritant is necessary to initiate the process of pearl formation.

Initially, pearl fishermen fished pearlfish (Pinctada margaritifera) from a sea shoal, carried them to a boat, opened them, and checked whether the individual contained a pearl or not. The opened shells were thrown into the sea or taken to the harbor for the production of mother-of-pearl.

Today it is possible to look 'into the belly' of the pearl mussel with small x-ray machines. When interest in mother-of-pearl waned, pearls became a target for fishing. Fishing was so intensive that in some regions the mother-of-pearl became extinct. But as early as 1920, Mikimoto of Japan developed a way to force the mother-of-pearl to produce jewels. A piece of epidermis is taken from a live mollusc, a 'pearl embryo' - preferably a piece of Mississippi mussel shell - is sewn around it, and implanted back into the mussel's leg. After a few years, the 'embryo' grows layers of mother-of-pearl and the resulting pearls have commercial value after two years, while it takes five years or more to get a good pearl. Based on this method, the breeding of so-called "artificial pearls" on an industrial scale has developed.

Artificial pearls have less commercial value, although they are usually indistinguishable from natural pearls. (Allegedly, this can be done by spectroscopic methods, because artificial pearls absorb less light in the ultraviolet range). In the 1980s, breeding of black-stranded pearlfish began in the Cook Archipelago, with the site chosen because certain atolls were particularly rich in black-stranded pearlfish. The leading atoll in this regard was Manihiki Atoll, whose inhabitants had been engaged in pearl and mother-of-pearl fishing for years.

Some Tuamoto and Tongareva and Suwarrow atolls also provide black pearls. In the 1980s, Manihiki became a 'pearl basin'. Pearl farms were established where pearl mussels live on ropes stretched underwater. From time to time they are looked after, checked for parasites, cleaned of excess algae and returned to the sea. After a few years the pearls are harvested and a new colony is established.