£32m doorstop

A gemstone found during a picnic and once used as a doorstep could fetch £32million at auction next month. Despite being only slightly bigger than a hen's egg, the Black Star of Queensland is one of the most valuable sapphires ever found. The 733-carat stone - encircled with 35 diamonds - has never been on the market since its discovery in 1938.

It was found by a Mrs Roy McKiney, who was on a picnic with her family in Queensland, Australia, when she stubbed her toe on a rock containing the gem. It spent several years being used as a doorstop before its owner realised its value. In 1948, the Black Star was acquired by two Armenian brothers and taken to the US, where it has been in a museum since 1985. Jack Armstrong, the expert handling the sale, said: 'To have a stone like this come on the market is like having a Raphael painting suddenly emerge.'