A collection of three rings, 19th century

A collection of three rings, 19th century, comprising: a ring set with an oval amethyst within a border of circular-cut chrysoberyls, mounted in gold in closed-back settings, size O; an elongated plaque ring set with opaline glass over a patterned foil background, to a border of cushion-shaped colourless paste stones, mounted in gold, size O; and a ring of navette design set with variously cut pink topazes and rose-cut marcasites, mounted in silver and gold, size P1/2, indistinct assay mark