Unusual Swiss 18k gold open faced keyless lever Circa 1940

Gold keyless lever by Vacheron Constantin
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A fine and elegant Swiss 18K yellow gold keyless dress watch with two-tone pink dial, circa 1940. Mechanical movement, 18 jewels, bimetallic compensation balance. 18 jewels, wolf’s tooth winding, straight line lever escapement, cut bimetallic compensation balance adjusted to temperature and five positions, blued steel Breguet balance spring, index regulator. Case polished, curved bezel, hinged gold cuvette.
Two-tone pink dial, applied gold baton indexes and Roman numerals, outer minute track, subsidiary seconds. Pink gold bâton hands. Dial and movement signed.
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Diameter: 47 mm
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Signed: Vacheron & Constantin Genève Swiss