Riker Brothers sapphire and diamond cluster ring. Centrally set with a diamond-shape step-cut natural unenhanced sapphire in an open back rubover setting with an approximate weight of 1.50 carats, further set with twenty round old cut diamonds in open back grain and rubover settings with an approximate combined weight of 0.70 carats, to a geometric cluster design featuring intricate openwork with millegrain edging, a decoratively pierced gallery and fancy shape open backholing, leading to openwork shoulders with a scrolling motif and flowing through to a ribbed flat shank. Tested platinum, maker's mark for Riker Brothers, American, circa 1920.
