Unlike most farmed pearls, natural pearls often stick to their parent’s shell as “blister pearls.” They’re also less smooth but because of their rarity, they’re no less valuable than their cultivated counterparts. “Only certain mollusk groups use a substance, called nacre, which gives gem-quality pearls their opalescent sheen,” said Chris Meyer, a marine invertebrate zoologist and curator of mollusks at the museum.īy collecting and analyzing nacreous pearls, scientists can learn more about how mollusks create these shiny gems and how that biological process could change as Earth’s waters warm. While all mollusks, including oysters, mussels, and clams can technically make pearls, only some saltwater clams and freshwater mussels are used to commercially grow cultured gem-grade pearls. Whitney curator of gems and minerals at the Smithsonian’s National Museum of Natural History.

If debris gets stuck in a mollusk and they can’t flush it out, they coat this debris in their own mother of pearl or shell material,” said Gabriela Farfan, environmental mineralogist and Coralyn W. “Pearl is a word we use for a shiny creation that a mollusk produces. But pearls - the most famous biological gems - come from the bowels of mollusks.

Most gems come from the bowels of the Earth, made by pressure and heat over millions of years. As with all gems, the less blemishes they have, the more valuable they are. Smooth pearls in the shape of orbs and ovals are usually created by bivalves, like mussels, in pearl farms.

Golden pearl farming spot