An 18.67 carats Colombian emerald and diamond ring, by Van Cleef & Arpels, 1920. Estimate £120,000 - 150,000 (€160,000 - 200,000). Photo: Bonhams.

The octagonal step-cut emerald, weighing 18.67 carats, within a delicate mount millegrain-set with single-cut diamonds and engraved decoration, unsigned, numbered 8752, rubbed French assay mark, ring size M

Accompanied by a report from SSEF stating that the emerald is of Colombian origin, with indications of clarity modification, moderate amount of oil in fissures. Report number 80660, dated 18 June 2015.

Bonham's. FINE JEWELLERY, 24 Sep 2015 12:00 BST - LONDON, NEW BOND STREET