A few years ago, the Gwich’in jeweler Tania Larsson was on the hunt for materials to create some new pieces. Specifically, Larsson was searching for dentalium shells—the long, tubular shells deriving from dentaliums, a type of marine mollusk. Only problem was, Larsson couldn’t find any; all of her usual suppliers, including various trading posts, were completely depleted of the increasingly-rare shells. But then, Larsson got a call: One seller had a good assortment up for grabs. The artist didn’t hesitate: “I was like, ‘can I buy them all?’”

In the Indigenous fashion world, dentalium shells—which resemble tusks, thanks to their curved shape and milky-white color—are considered just as precious as diamonds, if not more, due to how increasingly difficult they are becoming to find. “My most valuable shells are antique ones from North America, because those are thick and long,” says Larsson. “Those are not even like diamonds—they’re one-in-a-million.” It’s not just a question of rarity: dentaliums continue to be sought after for their unique histories and special meanings, too.

So, where exactly do these shells come from—and why are they considered more valuable than precious gems?