A woman purchased what she thought was a fake diamond ring at the West Middlesex Hospital in London in the 1980s. She paid just $13 for the large ring, and she wore it almost every day for 30 years. But, in 2017, the woman — who wished to remain anonymous — learned that the ring was actually a 26-carat diamond.

"It was only early on this year that she wanted to see if it had any value at all," Sotheby's Jessica Wyndham told BBC. "It was a total surprise to her when the jeweler said that looks like a diamond."

The ring was originally priced at over $400,000, but it was actually sold for $847,667 in an auction.