A  daimond ring, by Harry Winston. Photo Christie's Image Ltd 2012

Set with a modified marquise-cut diamond, weighing approximately 11.68 carats, flanked on either side by a tapered baguette-cut diamond, mounted in platinum. Estimate $300,000 - $500,000

Signed Winston for Harry Winston
With report 2145622285 dated 13 April 2012 from the Gemological Institute of America stating that the diamond is F color, VS1 clarity; accompanied by a working diagram indicating that the clarity may be improvable 

Christie's. Magnificent Jewels. 16 October 2012. New York, Rockefeller Plaza