Regarded as one of the most important Magnificent & Noble Jewels auction by Sotheby's in 30 years, the house has announced the sale of a rare emerald and diamond tiara on May 17, 2011.

Slated in Geneva, the tiara is composed of 11 Colombian emeralds and is estimated to bring around $5-10 million.

It is believed that the tiara was commissioned sometime during 1900, possibly from the renowned jewelers Chaumet, by Guido Count von Henckel, First Prince von Donnersmarck, for his second wife Princess Katharina.

The exceptionally rare 11 pear-shaped Columbian emeralds that compose the tiara weigh over 550 carats and may well have been one of the most precious collections of the Donnersmarcks. The jewelry collection of the royal family was known to be on a par with, or even to have exceeded, those of many of the crowned heads of Europe.