Lot 640. An important 16.56 carats Burma Royal Blue Sapphire and Diamond ring. Estimate HK$ 3,200,000 - 4,500,000 (€ 350,000 - 490,000). Photo: Bonhams.

Set with an oval-cut sapphire, weighing 16.56 carats, between half moon-shaped diamond shoulders, accented by brilliant-cut diamonds on the half hoop; estimated total diamond weight 2.30 carats total; mounted in platinum; size 6½.

Accompanied by a report from SSEF stating that the natural sapphire has no indications of heat treatment and originates from Burma (Myanmar). Report number 103451, dated 9 November 2018.

Accompanied by a Gübelin report stating that the natural sapphire has no indications of heat treatment and originates from Burma (Myanmar). Also, with an information sheet stating that large unheated sapphires of gem-quality are rarely found in nature, and the supply of these types of sapphires remain limited and difficult to find. Report number 18101046, dated 18 October 2018.

Accompanied by a GRS report stating that the natural sapphire is vivid 'GRS-type Royal Blue' colour, has no indications of thermal treatment and originates from Burma (Myanmar). Report number GRS2018-076787, dated 17 July 2018.