GENEVA, SWITZERLAND - MAY 11: A Chaumet emerald and diamond tiara, from circa 1900, the most important to be auctioned in 30 years, formerly in the collection of Princess Katharina Henckel von Donnersmarck and also believed to have been in the collection of Empress Eugenie, weighing in total 500 carats, valued at 5-10 million USD, is seen during the Sotheby's magnificent noble jewels and important watches auction preview held at Hotel Beau-Rivage on May 11, 2011 in Geneva, Switzerland. The watch and jewels auctions which include iconic watches from five centuries and some of the most important jewels of nobel provenance will take place respectively on the 15th of May and the 17th of May in Geneva. (Photo by Harold Cunningham/Getty Images)

GENEVA, SWITZERLAND - MAY 11:  A Chaumet emerald and diamond tiara, from circa 1900, the most important to be auctioned in 30 years, formerly in the collection of Princess Katharina Henckel von Donnersmarck and also believed to have been in the collection of Empress Eugenie, weighing in total 500 carats, valued at 5-10 million USD, is seen during the Sotheby's magnificent noble jewels and important watches auction preview held at Hotel Beau-Rivage on May 11, 2011 in Geneva, Switzerland. The watch and jewels auctions which include iconic watches from five centuries and some of the most important jewels of nobel provenance will take place respectively on the 15th of May and the 17th of May in Geneva.  (Photo by Harold Cunningham/Getty Images)