Josephine Johnson, manager of Rio Tinto's Argyle Pink Diamonds, holds the Argyle 'Phoenix' red diamond, one of the world's rarest gems, during a private viewing at a Sydney hotel May 17, 2013. The Phoenix, which could fetch several million dollars, is included in the 2013 Argyle Diamond collection, named after Rio Tinto's Argyle diamond mine in Western Australia where they were found. The entire collection of 64 red, pink, dark gray-blue, orangy-pink and purple-coloured diamonds, totalling 54.99 carats, is estimated to be worth tens of millions of dollars, according to Rio Tinto. [Photo/Agencies]

Josephine Johnson, manager of Rio Tinto's Argyle Pink Diamonds, poses with the Argyle 'Phoenix' red diamond, one of the world's rarest gems, during a private viewing at a Sydney hotel May 17, 2013. The Phoenix, which could fetch several million dollars, is included in the 2013 Argyle Diamond collection, named after Rio Tinto's Argyle diamond mine in Western Australia where they were found. The entire collection of 64 red, pink, dark gray-blue, orangy-pink and purple-coloured diamonds, totalling 54.99 carats, is estimated to be worth tens of millions of dollars, according to Rio Tinto. [Photo/Agencies]