When US billionaire Harold Dodge paid a record $825,000 (€567,000) for a pearl necklace in 1920, he can scarcely have thought it would halve in value 88 years later.

The Dodge heirs are selling the prized necklace in a Bonhams auction in December. The necklace is expected to sell for $500,000 at the bottom end, which after inflation, ruins the original investment.