18K yellow gold ring by Masriera featuring very fine plique-a-jour enamel in pastel colors, bezel set round cut rubies and diamonds, channel set step cut rubies, and bead set round cut diamonds in an openwork design, signed "Masriera" and stamped with serial no. "B-4319-B," sz. 6.75, 7.4 grams, accompanied by original box, certificate of authenticity, and Masriera catalogue