By Cynthia Unninayar
The Sea of Cortez, also known as the Gulf of California, separates the Baja California Peninsula — the second longest peninsula in the world — from the Mexican mainland. With approximately 4,000 kilometres of coastland, the gulf is one of the most diverse seas on the planet and is home to 5,000 species of micro-invertebrates. It is also home to a species of oyster, Pteria sterna, which produces pearls in a rainbow of colours.
During the Age of Discovery, European explorers searched the globe for untold treasures in lands across the oceans. One of the Spanish conquistadors was Hernán Cortés, who led the expedition that overthrew the Aztec empire in the early 16th century, winning Mexico for the crown of Spain. Among the riches he took back to Europe were pearls with the most intense colours ever seen.
These lustrous objects soon became New Spain’s most important export. Their prices exceeded that of the combined exports to the Old World of gold, silver and spices. Prized by queens, kings and nobility, these dark Mexican pearls were known as “The Queen of Gems and the Gem of Queens”.
To satisfy the growing demand in Europe, fishermen scoured the waters of the Gulf for the molluscs that produced these iridescent pearls. As a result of overfishing, the oyster beds were virtually depleted by the end of the 19th century and soon, thereafter, Mexican pearls basically disappeared from gem markets.
In an effort to save the industry, Gaston Vivés, a medical doctor of French origin, created an oyster farm near La Paz in 1903 — the same year that Japan’s Kochiki Mikimoto was perfecting his techniques for growing pearls. Vivés raised eight million black-lipped Pinctada mazatlanica oysters in a protected growing area. Unlike Mikimoto, Vivés did not implant them with beads to create pearls, but, since one in ten oysters, on average, produced a natural pearl, he obtained around 800,000 pearls a year. Alas, his farm was destroyed in 1914 — a casualty of the Mexican Revolution. In 1939, natural pearl fishing was banned altogether in an attempt to prevent the extinction of these unique molluscs.
Interest in the Sea of Cortez “gems” never dwindled, though, and experiments to cultivate nacreous pearls in Pinctada mazatlanica and Pteria sterna — the two species inhabiting the Gulf coastline — were conducted over the years. In 1993, four researchers (Sergio Farell, Manuel Nava, Douglas McLaurin and Enrique Arizmendi) from the Instituto Tecnologico de Estudios Superiores de Monterrey, ITESM, began cultivating pearls as a university project in Bacochibampo Bay near the city of Guaymas. Their efforts resulted in the successful harvesting of high-quality cultured pearls in the rainbow-lipped Pteria sterna oyster. T
his led, in 2000, to the establishment of a private company, Perlas del Mar de Cortez, in association with the ITESM. After the local ITESM closed in 2005, the original researchers took over the company and changed its name to Cultivadores Mexicanos de Perlas SC, while keeping the ‘Perlas del Mar de Cortez (PMC)’ as the brand name. It is the only saltwater cultured pearl farm in the Americas.
Since Mexican law prohibits the use of wild adult pearl oysters, pearl farming begins with the collection of spat. When molluscs reproduce, they release larvae into the water that swim around until they find a suitable structure to settle on. Once the larvae attach themselves permanently to a surface, they are called spat.
Workers at the farm collect the spat, which is later transferred to baskets where the baby oysters are protected and can feed on plankton in the waters of the gulf. After two years, a bead — 6mm to 10mm from a freshwater mollusc — and a piece of tissue from a donor oyster are grafted into the gonads of an oyster. It is then placed in a mesh basket and left in the ocean for another 18 to 26 months to ensure a good nacre thickness. Each oyster is cleaned five times a year by hand to keep it healthy.
At harvest, the average pearl size is about 9mm, with exceptional pearls reaching 12mm to 14mm. The colours range from opalescent silver, grey and gold/bronze to blue/cyan, emerald/olive green, violet and black, with various iridescent overtones of pink, purple, blue and green. Each pearl is unique and there are never two identical pearls. While some Sea of Cortez pearls resemble Tahitian cultured pearls, they can be distinguished by their distinctive red fluorescence under long-wave ultraviolet radiation. They also exhibit a greater range of iridescent colours, including some shades not shown by Tahitian cultured pearls.
The shimmering iridescent natural colours of Sea of Cortez pearls are not, in any way, enhanced. After removal from the shell, they are washed in water, soaked in mineral oil for six hours, and then dried. They are never subjected to bleaching, dyeing, coating or polishing. They are available in round, semi-round, baroque and drop shapes.
Only a small percentage of a harvest meets the required gem-quality criteria, which translates into about 4,000 pearls a year. This makes the Sea of Cortez pearls the rarest on Earth. If we compare their annual production to other types of pearls, we find: freshwater 1,800 tonnes; akoya 50 tonnes; Tahitian black pearls 12 tonnes; white and golden South Sea pearls 11 tonnes; Sea of Cortez pearls 0.004 tonnes or 4 kilograms. They are also the only pearls in the gem industry that qualify under the “Fair Trade Gems” protocol.
More than half of PMC’s production is sold locally, while other pearls are distributed by a few authorised dealers. The oyster meat is sold as food, considered a delicacy in the region, and the shells are made into buttons.
The company sells loose pearls as well as several lines of jewellery in classic and contemporary styles in silver and gold. It also produces mabe pearls, which are mostly set in silver by local silversmiths. (Photo courtesy: Perlas del Mar de Cortez unless otherwise specified)
← Back