A rectangular-cut emerald and diamond brooch, by Harry Winston. Photo Christie's Image Ltd 2014.

Set with a rectangular-cut emerald, weighing approximately 42.88 carats, within a pear-shaped diamond surround, mounted in rhodium plated 18k gold, with pendant hook for suspension, 1971. Estimate $700,000 – $1,000,000

With report CS 59114 dated 3 February 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 Classic Colombia. Minor clarity enhancement, traditional type 

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