Lot 251. A 11.00 carats rectangular-cut Type IIa diamond ring, by Harry Winston. Estimate $700,000 – $900,000. Photo Christie's Image Ltd 2016.

Set with a rectangular-cut diamond, weighing approximately 11.00 carats, flanked on either side by a cut-cornered triangular-shaped diamond, ring size 4 1/2, mounted in platinum, in a Harry Winston navy leather case. Signed H.W. for Harry Winston

Accompanied by report no. 7115444 dated 9 December 2015 from the GIA Gemological Institute of America stating that the diamond is D color, VVS1 clarity

With a supplemental letter from the Gemological Institute of America 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 I and the 105.60 carat Koh-i-noor, are examples of Type IIa.

Christie's. MAGNIFICENT JEWELS & THE JUBILEE RUBY, 20 April 2016, New York, Rockefeller Plaza