James Humphries, 34, of Newquay, England, said he bought the oysters -- which he described as "the perfect hangover cure" -- from E Rawle & Co. fishmongers Saturday morning after a night of drinking, and discovered a pearl while eating his breakfast, The Mirror reported Tuesday.
I thought a filling had fallen out. It was only when I spat it out that I discovered it was a pearl," he said. "It's small, but perfectly formed and I absolutely love it."
Paul Cox of the National Marine Aquarium in Plymouth said Humphries' discovery was a rare find.
"It's extremely rare for pearls to occur naturally in the wild," he said. "Most of the pearls you see are cultivated or come from pearl oysters. I've never come across anyone who has found a wild pearl before. It's extremely unusual and he's a very lucky man."
Heather Bell of Little Gem jewelers in Newquay said it is difficult to put a price on the pearl.
"It's difficult to put an exact price on this, but given the rarity, it's a priceless find for James," she said.
Humphries said he plans to keep the pearl.
"I'm thinking of getting the pearl made into a piece of jewelry -- possibly a little silver fish with the pearl for its eye," he said.