Exhibition curator Caroline de Guitaut poses with the Cullinan III and IV brooch at the Queen's Gallery in Buckingham Palace, London May 15, 2012. A special exhibition "Diamonds: A Jubilee Celebration" will run from June 30 - July 8 and July 31 - October 7, in celebration of Queen Elizabeth's Diamond Jubilee anniversary. REUTERS/Stefan Wermuth (BRITAIN - Tags: ENTERTAINMENT ROYALS SOCIETY)