8.31 carats Colombian emerald and diamond ring. Estimate HK$3,500,000 - 4,500,000 (US$450,000 - 577,000). Photo Tiancheng International

Centring on an octagonal step-cut emerald weighing 8.31 carats, flanked by two emerald-cut diamonds weighing 2.05 and 2.00 carats respectively, decorated with brilliant-cut diamonds on the shoulders, mounted in platinum and 18 karat yellow gold. Ring size: 5¼

Accompanied by SSEF report numbered 62682, dated 9 March 2012, stating that the 8.31 carat emerald is natural, Green colour of medium strong saturation, of Colombian origin, with no indications of clarity modification;

AGL report numbered CS83810, dated 12 February 2015, stating that the 8.31 carat emerald is natural, Green colour, of Classic Colombian origin, with no indications of clarity enhancement;

GIA reports numbered 6167650358 and 1203064259, dated 2 October 2014 and 2 June 2015 respectively, stating that the 2.05 and 2.00 carat diamonds are F colour, VVS1 clarity, the 2.05 carat diamond with Excellent Polish, the 2.00 carat diamond with Excellent Symmetry.

Tiancheng International. HONG KONG AUTUMN AUCTION, Jewellery and Jadeite