A Colombian emerald and diamond ring. Estimate CHF700,000 – CHF900,000 ($734,473 - $944,323). Photo Christie's Image Ltd 2015

Set with a cut-cornered square-cut emerald, weighing approximately 7.21 carats, to the square-cut diamond shoulders, weighing approximately 1.82 and 1.78 carats, mounted in platinum, ring size 6 

Accompanied by report no. CS 52051 dated 13 February 2015 from the AGL American Gemological Laboratories stating that the emerald is of Colombian origin, with no indications of clarity enhancement 

Report no. 1156371261 dated 18 April 2013 from the GIA Gemological Institute of America stating that the 1.82 carat diamond is E colour, VVS2 clarity

Report no. 6157685984 dated 25 September 2013 from the GIA Gemological Institute of America stating that the 1.78 carat diamond is E colour, VVS1 clarity

Christie's. GENEVA MAGNIFICENT JEWELS, 13 May 2015, Geneva