For at least 164,000 years, oysters have been part of the human diet, but people have been finding pearls in oysters for much longer — as early as 2300 BC when Chinese royalty received them as gifts.

A pearl does not begin as something precious. It begins as a problem. Inside an oyster, a tiny particle slips in and settles where it does not belong. It might be a parasite, a rough fragment, or ...