Lot 315. Very fine 21.34 carats Colombian emerald and diamond ring, Harry Winston. Estimate 165,000 — 225,000 CHF. Photo: Sotheby's

Set with a step-cut emerald weighing 21.34 carats, between triangular diamond shoulders, size 48, signed Winston, maker's marks for Jacques Timey.  

Accompanied by SSEF report no. 90973, stating that the emerald is of Colombian origin, with no indications of clarity modifications, together with an appendix letter.

Note"The described emerald exhibits a remarkable size and weight of 21.346 ct, combined with an attractive and homogeneous green colour and a fine purity... In addition to these qualities, this emerald shows no indications of clarity modification in fissures at the time of testing, which is a further sign of rarity".

Excerpt from the SSEF appendix letter

Sotheby's. Magnificent Jewels and Noble Jewels, Session 3, Geneva, 16 May 2017, 07:00 PM