A pearl is a hard object produced within the soft tissue of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls also occur.
The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, fine, admirable, and valuable.
The most valuable pearls occur spontaneously in the wild, but they are extremely rare. Cultured or farmed pearls from pearl oysters make up the majority of those that are currently sold. Pearls from the sea are valued more highly than freshwater pearls.
Imitation or fake pearls are also widely sold in inexpensive jewellery, but the quality of their iridescence is usually very poor, and generally speaking, artificial pearls are easily distinguished from genuine pearls.
Pearls have been harvested and cultivated primarily for use in jewellery, but in the past they were also stitched onto lavish clothing. Pearls have also been crushed and used in cosmetics, medicines, and in paint formulations.
Pearls are closely linked to humans since prehistoric time. Evidences suggest that, pearl shells were used as decorative objects during ancient times in Egypt. Pearls re also featured in religious texts like Bible and Koran. Also the origin of pearls is explained in mythological and cosmological terms.
During the reign of Alexander the Great there was a marked increase in the trade and transport of pearls to the Western world from the Red Sea and the Middle East. Pearls were symbolic of power and purity during the middle Ages and many royals adorned themselves with pearl jewels.
An important period in pearl history were the first voyages of Christopher Columbus and other Spaniards in the 15th and 16th centuries when they discovered pearls and pearl oyster banks in Central and South America. This generated great wealth for the Spanish crown and triggered what is known as the “Pearl Age” amongst European royals and aristocrats.
Although there were numerous attempts at culturing pearls, the first to successfully achieve this feat and market a product was Mikimoto using the Mise-Nishikawa method in 1916. With the help of Japanese expertise cultured pearl farming expanded to other countries. Affordability of cultured pearls led to gradual demise of the natural pearl trade from the 1920s onwards.
Six species of pearl oysters occur along the Indian coasts,
Pearl oysters of the genus Pinctada are cosmopolitan in distribution. They occur in several seas of the tropical belt and in the sub-tropical region. Although a number of species of pearl oysters have been identified, only a few have been found to produce pearls of good quality with commercial value.
In the Indian waters six species of pearl oysters occur but only P. fucata has contributed to the pearl fisheries in the Gulf of Mannar and Gulf of Kutch.
Pearls have been known to mankind since the beginning of civilization. They are highly esteemed as gems for their beauty and splendour. These structures are secreted by the mantle (i.e., the skin) of pearl oysters in response to irritations caused by external or internal stimuli such as sand grains, mollusc eggs, parasites, detritus, and other foreign particles. Many attempts have been made to culture pearls in freshwater mussels.
India has one of the highest demands for pearls for setting in jewellery. The pearl oyster fisheries are located in two main areas:
1) The Gulf of Mannar of Tuticorin coast and
2) The Gulf of Kutch on the northwest coast
The pearl oysters are found in two different environments in two localities, at depths up to 23 meters in the Gulf of Mannar, in the intertidal zone in the Gulf of Kutch. These bivalves form large beds on hard substrata in the Gulf of Mannar, while they are sparsely distributed in the Gulf of Kutch. The pearl oyster resources in the two areas have been fished for pearls until the early 1960's.
The techniques of pearl oyster farming and pearl culture are not widely known. In India, interest in pearl culture began at the start of this century. Several studies have been conducted by the Madras Fisheries Department in the 1930s. In 1972, the Central Marine Fisheries Research Institute (CMFRI) took up intensive research on pearl culture at Tuticorin achieving a breakthrough in July 1973 when it produced free spherical cultured pearls by employing the mantle graft implementation technique.
The development of the pearl oyster hatchery technology in India in 1981 opened the way for large and commercial scale culture of this bivalve species. Based on the technical know-how provided by the CMFRI, a company has been established at Tuticorin to produce cultured pearls.
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