Large Swiss 18k gold open faced lever chronograph Circa 1923

Gold chronograph by Vacheron & Constantin
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A very fine, rare and large Swiss 18 carat gold open faced keyless lever watch with chronograph, circa 1923. Jeweled mechanical movement, swan neck micrometer regulator. Gold cuvette with inscription. White enamel dial with Arabic numerals, two subsidiary dials for constant seconds and 30 minute register. Plain case, monogrammed to the back. Case, dial, cuvette and movement signed, case and movement numbered.
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Diameter: 52.5 mm
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Signed: Vacheron & Constantin Genève Suisse Chronomètre