Sea of Cortez Pearls are saltwater cultured pearls from the rainbow-lipped Pteria sterna oyster, native to Mexico's Sea of Cortez. This oyster is also known as the Western Winged Pearl Oyster and Concha Nácar. Mexican Pearls display two features: an unusually compact structure of its aragonite crystals –seen at 500 nanometers- and the display of “spiraled” sub-patterns like a fingerprint, which are unique to these pearls.
Spanish captain Fortun Jimenez marveled at the pearls he saw on the locals when he visited what he termed the “Sea of Pearls” , later christened as the "Mare Bermejo de Cortés" (loosely translated as the "Red Sea of Cortez" and now officially known as the Gulf of California), in 1533. Natural pearls were harvested for the next 300 years, becoming an important export. Unfortunately, the construction of the Hoover Dam depleted nutrients in the Gulf of California, diminishing natural pearl production in the area. To protect the oysters, the government banned harvesting of natural oyster beds in 1939. The Monterrey Technical Institute in Guaymas began studying pearl culturing in 1993, producing the first experimental round pearls in 1996. Only 4,000 pearls are cultured in these waters each year, making them the rarest of cultured pearls. Only 30 percent of the production is round.
The average size of the Sea of Cortez pearl is 8.9 mm, ranging in size from 8.3 to 9.8 mm, but they can get as large as 14.3 mm. Sizes above 10 mm in diameter account for only 5% of a pearl harvest. The pearls are completely untreated; no polishing, bleaching, irradiation, coating or artificial dyeing is performed on them. The Sea of Cortez Pearl is the only pearl in the gem industry that completely qualifies under the Fair Trade Gems protocols.
Photos courtesy of Perlas del Mar Cortez