A 4.20 carats Colombian emerald and diamond 'Trombino' ring, by Bulgari. Estimate: $60,000 – $80,000. Photo Christie's Image Ltd 2015

Set with a rectangular-cut emerald, weighing approximately 4.20 carats, within a circular-cut diamond surround, to the baguette-cut diamond shoulders, ring size 6, mounted in platinum - Signed Bulgari

Accompanied by report no. CS 70050 dated 1 September 2015 from the AGL American Gemological Laboratories stating that it is the opinion of the Laboratory that the origin of this emerald would be classified as Colombia, withminor clarity enhancement, traditional type

With duplicate report no. 48681 dated 21 May 2007 from the SSEF Swiss Gemmological Institute stating that it is the opinion of the Laboratory that the origin of this emerald would be classified as Colombia, with indications of clarity modification

 Christie's. IMPORTANT JEWELS, 20 October 2015, New York, Rockefeller Plaza