Four gem-set gold rings

Four gem-set gold rings, comprising: a sapphire and diamond cluster ring, size M, inscribed Cartier, numbered 53 416952, Swiss assay mark for 18ct gold; an 18ct gold band rubover set with three oval rubies, spaced by brilliant-cut diamonds, size R, British hallmark; a gold ring tension-set with an oval orange sapphire, size R1/2, stamped 750; and a ring set with a step-cut emerald between princess-cut diamond shoulders, size Q, stamped 18kt