When a London woman realized the true value of her costume jewelry, her life changed dramatically. Over thirty years ago, she bought a captivating ring at the Middlesex Hospital Flea Market for just £13, around $17, unaware of its real worth.

She wore the ring daily, considering it a talisman. One day, an enigmatic man fixated on the ring followed her at the grocery store, alarming her. Though she escaped, this encounter fueled her suspicions.

Later, forgetting the ring at home, she decided to get it appraised at Sotheby’s London. To her shock, experts identified the ring as a 26-carat cushion-shaped white diamond from the 19th century. Its antique cut had obscured its true brilliance, leading many to misjudge its value.

Jessica Windham, head of Sotheby’s jewelry department, revealed that the diamond, initially bought for £13, could fetch up to £350,000 ($450,000). At auction, it sold for an astounding £656,750 ($850,000), granting the woman financial stability she had never dreamed of.

This story highlights the hidden value in seemingly ordinary items. Experts recommend checking materials, condition, age, and brand, and seeking professional appraisals to uncover the potential worth of costume jewelry.