Woman discovers ring bought at flea market is valuable diamond

LONDON (KGO) -- A woman bought a sparkly ring at a flea market in London thinking it was a fun piece of costume jewelry. In fact, she wore it every day for about 30 years, not knowing that her $13 ring was not a cubic zirconia.

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Turns out the over-the-top diamond is the real deal - a 26 carat antique white diamond.

She says she finally took it to Sotheby's after a jeweler saw it and told her it could be very valuable.

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It sure is.

The diamond is set to hit the auction block next month, expected to fetch more than $450,000.