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Cultured · Saltwater

Sea of Cortez pearls

Rare cultured pearls from Mexico's rainbow-lipped oyster, grown near Guaymas, Sonora. Brown to dark gray with violet, blue, yellow and green overtones, in very small numbers.

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By The Perfect Pearls editors · Updated · How we check our facts

Illustration of a typical sea of cortez pearl. Move your pointer to turn the light.

At a glance

WaterSaltwater
MolluskPteria sterna (rainbow-lipped oyster)
WhereBacochibampo Bay near Guaymas, Sonora, Mexico
Typical sizeAbout 7 to 11 mm (2001 to 2002 harvests)
ShapesFew round; most off-round (5% round or near-round in 2001, about 25% in 2002)
How it startsBead-nucleated
0 mm5 mm10 mm15 mm20 mm

Typical size range from GIA. See sizes at actual size.

GrayBrown

Sea of Cortez pearls are cultured in the native rainbow-lipped oyster, Pteria sterna, at a farm in Bacochibampo Bay, about 8 km from the port town of Guaymas, Sonora, Mexico (GIA).

What they look like

GIA describes a brown or gray to dark gray bodycolor with overtones of violet, blue, yellow and green. In the harvests GIA studied, sizes ran from about 7 to 11 mm, and only 5% were round or near-round in 2001, rising to about 25% in 2002.

A small, young farm

Researchers began developing the method in 1993, and the first dozen experimental full-round cultured pearls were shown at the Tucson gem show in February 1996. GIA reported output of about 4,000 cultured pearls a year, expected to stabilize at around 10,000 a year. These figures come from GIA's study of the early 2000s, so treat them as history rather than today's numbers.

What people paid for sea of cortez pearls

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Frequently asked questions

What are Sea of Cortez pearls?

Cultured pearls from the rainbow-lipped oyster Pteria sterna, farmed near Guaymas, Sonora, Mexico. Brown to dark gray with violet, blue, yellow and green overtones (GIA).

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Sources

Checked October 22, 2026. How we check our facts.