One lucky woman who paid $15 for a large "costume jewelry" ring got the surprise of her life after learning the ring is Watch Cheerleaders Gone Bad XXX Movieworth way, way, WAY more than that.

Thirty years ago, an unnamed owner bought an "exceptionally sized" stone from a flea market at the West Middlesex hospital in west London, The Guardianreports. She wore the ring for years while shopping and even doing chores before bringing it into Sotheby's after a jeweler told her it could be valuable. And boy, is it valuable.

The ring, it turns out, is worth $450,000.

A ring she bought for $15 is worth almost half a million...

The 26.27, cushion-shaped, carat white diamond ring will be auctioned off on June 7. The owner had no idea that it could be real because the 19th century stone was not cut to show off its shine.

The head of the Sotheby's London jewelry department, Jessica Wyndham, explains, "With an old style of cutting ... the light doesn't reflect back as much as it would from a modern stone cutting. Cutters worked more with the natural shape of the crystal, to conserve as much weight rather than make it as brilliant as possible."

She adds, “They had been to quite a few car boot sales [flea markets] over the years. But they don’t have any history of collecting antiques and they don’t have any history of collecting diamonds. This is a one-off windfall, an amazing find.”

Sotheby's had the diamond tested at Gemological Institute of America, and although it seems to have been cut in the 19th century, how it arrived at the car boot sale is still unknown.

Wyndham said the owners are "incredibly excited. Anyone would be in this position. It’s a life-changing amount of money. No matter what your background is or what your past experiences have been, it’s going to revolutionise someone’s life."

One woman's trash is the... same woman's treasure, we guess.

[H/T: The Guardian]