Lot 2042. An important 18.69 carats Colombia Muzo rectangular-cut emerald and diamond ring, by Harry Winston. Estimate HKD 7,800,000 - HKD 12,000,000 (USD 1,010,527 - USD 1,554,656). Photo Christie's Images Ltd 2016.

Set with a rectangular-cut emerald, weighing approximately 18.69 carats, flanked by trapeze-cut diamonds, mounted in platinum and gold, ring size 5. Signed Winston for Harry Winston

Accompanied by report no. CS 61999 dated 24 June 2014 from the AGL American Gemological Laboratories stating that the emerald is of Colombia origin, with no clarity enhancement; also accompanied by a letter stating that the emerald has received the highest origin determination issued by AGL. This gemstone exhibits a very fine, saturated, slightly bluish green color that is reminiscent of high-quality emeralds from the Muzo mining area. In addition, it has been fashioned into the traditional form of a rectangular emerald cut, which represents the intrinsic quality and color of this gem to its fullest 

Report no.73804 dated 28 March 2014 from the SSEF Swiss Gemmological Institute stating that the emerald is of Colombia origin, with no indications of clarity modification; also accompanied by an appendix stating that the natural emerald possesses extraordinary characteristics and merits special mention and appreciation. The emerald exhibits a remarkable size and weight, combined with an attractive saturated colour and a fine purity, rarely encountered in Colombian emeralds of this size. The few inclusions found by microscopic examination represent the hallmarks of Colombian emeralds from the famous mining areas as Muzo, Coscuez, and Chivor, all located in the green foothills of the Cordillera Oriental in the Colombian Andes. Its saturated green colour is due to a combination of well-balanced trace elements in the stone, typical and characteristic for the finest emeralds of Colombia. A natural emerald from Colombia of this size and quality is very rare. 

Christie's. Hong Kong Magnificent Jewels, 29 November 2016, Hong Kong, HKCEC Grand Hall