A BOHEMIAN STAINED-AMETHYST DOUBLE-PORTRAIT GOBLET AND COVER for the Polish market, engraved with profile portraits to left and right inscribed above REGINA POLONIARIUM. MARIA CASIMIRIA.D.G. and IOAN III.D.G.REX POLON. M.D.L.RUS.PRUS.MAS within oval line cartouches divided by tied foliage, on an amethyst rectangular panel with canted angles, the reverse with polished pillared flutes and inscribed with crowned initials on cut roundels, supported on a waisted octagonal stem and spreading foot, the underside with alternate amethyst and clear ornament, the gadrooned domed cover and mushroom finial flashed in amethyst, circa 1845