Magnificent and exceptionally rare fancy deep blue diamond - Photo Sotheby's

The fancy deep blue briolette diamond weighing 10.48 carats. Estimation: 3,280,000 - 4,200,000 CHF

Accompanied by a duplicate of GIA report no. 11736022, stating that the diamond is Fancy Deep Blue, Natural Colour, Flawless.

NOTE DE CATALOGUE: By definition, a precious gemstone must be beautiful, rare and durable. These criteria are more than fulfilled by the exceptional diamond shown here: a magnificent Fancy Deep Blue.

Diamonds are found in a variety of colours, each shade determined by their atomic structure. The blue diamond presented here, which to use the correct terminology is a Fancy Deep Blue, is an exquisite example, unsullied by secondary colours. Scientifically speaking the blue is due to the replacement of carbon atoms by boron in the crystal lattice of the stone, effecting its absorption of colour. Looked at aesthetically, however, this stone is truly beauty personified. Cut as a superb drop-shaped briolette, its many faceted surface, designed to reflect and refract light, has the added virtue of being flawless and, in terms of polish and symmetry, has been awarded the highest possible grade by the Gemological Institute of America.

Sotheby's; Magnificent Jewels. Genève | 14 nov. 2012 www.sothebys.com