The Pink Legacy, an exceptionally large pink diamond, is set to go under the hammer at Christie's in Geneva next week, when it is expected to bring in up to $50 million.

At nearly 19 carats, the vividly coloured gem is extraordinary, Jean-Marc Lunel, an international jewellery specialist at Christie's said. "If you consider that most pink diamonds weigh less than a carat, it is really something," he said. The gem, which on November 13 will be offered at auction for the first time, has been estimated at between $30 million and $50 million.