Nacreous Natural Pearls

Natural pearls were the economic mainstay of several Persian Gulf countries before oil began to take their place in the early 1900s. At great risk to their health and lives, divers descended to Gulf mollusk beds to harvest shells and the natural pearls a relative few contained. The pearls were highly prized by royalty and the wealthy in Europe, India, and what we now call the Middle East. Their source mollusk was Pinctada radiata. Fishermen still find a few P. radiata natural pearls and fewer still from P. margaritifera, which is also native to the Gulf.

Some species in the Pinnidae family are called “pen” pearls or “pin” pearls, probably a shortening of the family name. One of these is the Pinna nobilis species, native to the Mediterranean Sea. It’s harvested for food, but occasionally it yields natural pearls. The pearls can be as large as 7 mm and might be white, reddish, orangy, or tinted pink.

Atrina tuberculosa, also called Atrina maura, is another species in the Pinnidae family. It’s found on the Pacific Coast of Mexico and produces oval and button-shaped natural pearls that rarely measure more than 4 mm in their longest dimension. Their colors are distinctively dark—often jet-black—with a green, violet, or deep red secondary color.

Maha Tannous/GIA
These natural saltwater pearls from the Cook Islands formed in P. maculata.