An emerald and diamond trilogy ring, claw-set with a rectangular step-cut emerald with canted corners, 8.7 x 7.0 x 4.6 mm, flanked by angled shoulders further set with brilliant-cut diamonds, gallery chased with scrolled foliate, leading to applied serpent motifs on tapering shank, two-toned metal marked '18K', size O, 12.4 grams.