'Sky Blue' diamond seen fetching $25 million at auction

A rare "fancy vivid blue" diamond ring goes on display in London this week ahead of a November auction where it is seen fetching up to $25 million (20.62 million pound). The stone, named "The Sky Blue Diamond", weighs 8.01 carats and is mounted on a ring by jeweller Cartier. "It really is the colour of a summer sky with this beautiful brilliance and subtlety about the stone," said David Bennett, worldwide chairman of Sotheby's International jewellery division.