Swiss gold perpetual calendar with moon phases Circa 1951

Gold open faced  complicated watch by Patek Philippe
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A fine and rare Swiss 18 carat rose gold open faced keyless watch with perpetual calendar and moon phases, circa 1951. Mechanical movement stamped twice with the Geneva seal, 18 jewels, bimetallic compensation balance. Silvered matte dial applied rose gold Arabic and dot numerals, four subsidiary dials for month and leap year, day, date and moon phases with constant seconds. Plain case, snap on back. Case, dial and movement signed, case and movement numbered.
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Diameter: 46 mm
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Signed: Patek Philippe Genève