Lot 209. A 21.26 carats sugarloaf cabochon Colombian emerald and diamond ring. Estimate CHF500,000 – CHF600,000 ($514,205 - $617,045). Photo Christie's Image Ltd 2016

Set with a sugarloaf cabochon emerald, weighing approximately 21.26 carats, between trapeze-shaped diamond shoulders, ring size 6, mounted in platinum and gold

Accompanied by report no. CS1072695 dated 3 January 2016 from the AGL American Gemological Laboratories stating that the origin of the emerald is Colombia, with minor amount of oil, and a 'Jewel Folio'.
Report no. 15120220 dated 30 December 2015 from the Gübelin GemLab stating that the origin of the emerald is Colombia, with indications of minor clarity enhancement. 

Christie's. GENEVA MAGNIFICENT JEWELS, 18 May 2016, Geneva