Magnificent diamond. Photo Sotheby's

The cushion brilliant-cut diamond weighing 70.33 carats, mounted as a ring, size 511/2. Estimation 10,700,000 — 14,300,000 CHF

Accompanied by GIA report no. 5151832545, stating that the diamond is D Colour, Flawless, Type IIa, Excellent Polish, Excellent Symmetry.

Introduced at the beginning of the 20th century, the modern cushion-cut derives from ancient cushion-cut diamonds, sometimes referred to as 'old mine' cuts. The most famous predecessor of today’s cushion-cut is the 140.64 carat Regent diamond, formerly part of the French Crown Jewels, currently conserved at the Louvre, Paris. Discovered in Golconda, India in 1698 and sent to England to be cut between 1704 and 1706, the Regent became one of the first important examples of cushion-shaped diamonds. Probably developed in the 17th century, this cut slowly replaced the former dominant style of faceting, known as step-cutting. This experiment with perpendicular cuts, as opposed to horizontal ones, ultimately led to the development of the true round brilliant, in the late 19th century.

This magnificent 70.33 carat cushion brilliant diamond has not only received the highest colour and clarity grade from the GIA for white diamonds, D Colour, Flawless Clarity, but has also been found to be part of the rare Type IIa subgroup. Stones of this group, which comprise less than 2% of all gem diamonds, are chemically the purest of all diamond crystals and often have extraordinary optical transparency.

Sotheby's. Magnificent Jewels and Noble Jewels. Genève, 13 mai 2014 - http://www.sothebys.com/