A colour-change sapphire and diamond ring by Boucheron

A colour-change sapphire and diamond ring by Boucheron, c1940, the carved colour-change sapphire cabochon set within a surround of diamonds in fluted yellow gold mount, signed Boucheron Paris, with rubbed maker's lozenge and French control mark, size O

Accompanied by report number 80259-64 dated 5 March 2020 from GCS stating that the carved cabochon-cut sapphire weighs approximately 2.10cts and is a natural colour-change sapphire, appearing blue in daylight and purple in incandescent light. with no indications of heat treatment. Origin: Sri Lanka (Ceylon)