At the event, they poured 400 flutes of champagne, each with a cubic zirconia in the bottom -- except one, which held a diamond donated by Continental Wholesale Diamond.
An 80-year-old attendee named Miriam, who declined to give her last name, didn't know she held the winning glass until the diamond was sliding down her esophagus, WPTV reported.
"We were laughing, and I wasn't paying attention and I took a swallow," Miriam said.
Patrons finished their champagne, and no one knew where the diamond was.
"We were going table to table," said Andrew Meyer, partner at Continental Wholesale Diamond. "In the end, there was no diamond."
That's when Miriam had to spill the beans about her champagne gulp.
"I thought, someone will win this and I won't have to tell them," Miriam said. But when the diamond didn't turn up, she realized that the diamond was probably swimming its way through her digestive tract.
Miriam rushed to the hospital, where she learned that diamonds don't show up on an X-ray.
The diamond didn't turn up until Miriam went in for a routine colonoscopy.
"Be on the lookout for it, just in case," she told the doctor.
Her doctor found it -- but to be sure it wasn't another CZ, Miriam took it to the jeweler.
"She came in with it in a biohazard bag, and it wasn't even cleaned," said Joy Pierson, the store's other partner.
It was tested after being washed and steamed.
"Turned out to be the Real McCoy," Miriam said.
Miriam said she plans to keep the diamond in her family -- just not inside it -- where it will become an heirloom with quite the history.