Jewellery, Watches and Objects of Vertu to include the personal archive of Louis Osman, goldsmith and architect

A violet blue colour change sapphire and diamond cluster ring, the oval mixed-cut sapphire claw set within a cluster surround of old brilliant-cut diamonds, between trifurcated shoulders, mounted in 18ct gold, shank hallmarked, accompanied by a report by GCS confirming the sapphire is of Sri Lankan origin, with no evidence of treatment, sapphire weight approximately 7.1 carats, ring size N. £3000-5000

The report from the Gemmological Certification Services, numbered 78127-61 and dated 27.10.17, confirms the sapphire is a natural colour change sapphire, of Sri Lankan origin and with no evidence of heat treatment.