A Spectacular Diamond Pendant Necklace. Photo: Christie's Images Ltd 2014.

Suspending a briolette-cut diamond, weighing approximately 50.05 carats, with pavé-set diamond terminals, from trapeze and triangular-cut diamonds, to the black cord neckchain, mounted in platinum, 15¾ ins. Estimate: $5,500,000 – $7,500,000

With report 2155872567 dated 15 January 2014 from the Gemological Institute of America stating that the diamond is D color, Flawless clarity, with excellent polish and excellent symmetry.

Accompanied by a supplemental letter stating that the diamond has been determined to be a Type IIa diamond. Type IIa diamonds are the most chemically pure type of diamond and often have exceptional optical transparency. Type IIa diamonds were first identified as originating from India (particularly from the Golconda region) but have since been recovered in all major diamond-producing regions of the world. Among famous gem diamonds, the 530.20 carat Cullinan and the 105.60 carat Koh-i-noor, are examples of Type IIa

Christie's. MAGNIFICENT JEWELS, 16 April 2014, New York, Rockefeller Plaza - www.christies.com