Oscar Heyman Brothers sapphire and diamond Screw ring. Set with a round old cut diamond to centre in an open back platinum claw setting with a weight of 0.75 carats, encircled by eighteen tapered channel set baguette cut diamonds in open back rubover settings with a combined weight of 1.00 carats, spiraling with a further encircling row of eighteen tapered channel set baguette cut natural unenhanced sapphires with an approximate combined weight of 1.10 carats. The total approximate diamond weight is 1.75 carats, to a stepped circular ballerina cluster with an openwork gallery and intricate pierced backholing, flanked by split shoulders tapering down to a solid ridged shank. Marked 18 carat yellow gold and platinum, maker's mark for Oscar Heyman Brothers, numbered '26389', American, circa 1960, accompanied by Oscar Heyman Brothers authenticity certificate.
