A cushion-cut ruby and diamond ring. Photo: Christie's Images Ltd 2014.

Set with a cushion-cut ruby, weighing approximately 6.25 carats, flanked on either side by a shield-shaped diamond, within a circular-cut diamond surround to the circular-cut diamond gallery and hoop, mounted in white gold, ring size 5¾. Estimate $1,000,000 – $1,500,000

With report CS 58693 dated 16 January 2014 from the American Gemological Laboratories stating that it is the opinion of the Laboratory that the origin of this material would be classified as Burma (Myanmar). Heat enhancement: None

With report 0608707 dated 22 August 2006 from the Gübelin Gem Lab stating that gemmological testing revealed characteristics consistent with those of rubies originating from Burma (Myanmar). No indications of heating; accompanied by a supplemental appendix attesting to the rarity of the ruby

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