CHEVALIERE A platinum and 18k gold ring set with an octagonal shaped sapphire weighing approximately 10 cts. A platinum and 18k gold ring set with an octagonal shaped sapphire weighing approximately 10 cts. C.G.L. certificate stating: origin Ceylon (Sri Lanka), colour "vivid blue", no heat. RC : Dimensions of the stone: 12.8 x 9.4 x 7.8 mm approx. Partially legible hallmark (part of a hallmark of a master who worked for the House of Tabbah). TDD: 59 - 60; US: 9 (changeable). Gross weight: 22.7 g (Pt - 950 and 18k - 750).