The gem bought at a flea market is expected to fetch about 350,000 pounds ($454,000) when it is auctioned by Sotheby's next month.

LONDON — Some people have all the luck.

 

Consider the person who dropped about 10 pounds about $15 around 30 years ago on what was thought to be a piece of costume jewelry — it turned out to be a 26.27 carat white diamond.

 

The gem bought at a flea market is expected to fetch about $454,000 when it is auctioned by Sotheby's next month.

 

The buyer had no idea of the ring's value because 19th-century diamonds were not cut to show off their brilliance and clarity.

 

The auction house's jewelry department chief, Jessica Wyndham, said Monday the owner wore it on a daily basis, unaware that it was a real diamond.

 

She called it "an amazing find." The owners have asked not to be identified.