Art Deco 2.40 Carat Old Cut Diamond & Onyx Ring, circa 1920This stunning, stunning diamond and onyx ring simply aches with Art Deco charm. The old European cut diamond in the centre is rubover and milgrain set in platinum, and sits at the centre of a large rectangular bed of deep black onyx a stunning contrast between the brightness of the diamond and its surround. The head of the ring sits on a simple double gallery, leading to a slim platinum shank. There are some inclusions in the diamonds (these are seen