An onyx and diamond set cocktail watch, 1920s, the small silvered tonneau-shaped dial with black Arabic numerals, unsigned jewelled movement, case stamped platinum, with a oval bezel and hinged shaped panel shoulders, millegrain set throughout with single-cut diamond and accented with cabochon triangular and rectangular-shaped onyx, to a later narrow black leatherette strap, wristwatch head length, including shoulders, 42mm. £300-£500