Fine keyless 18 carat yellow gold Swiss pocket watch circa 1918

Keyless yellow gold Swiss pocket watch
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A very fine keyless, 18 carat yellow gold pocket watch, made by Vacheron & Constantin, Genève, circa 1918.
Four-body, bassine, polished case with engine turned case back. Hinged gold cuvette.
Silver dial with bold upright Arabic numerals, outer minute track and subsidiary seconds. Blue steel Breguet hands.
Frosted gilt movement with 17 jewels, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring and an index regulator.
Dial, case, cuvette and movement signed.
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Diameter: 50 mm
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Signed: Vacheron & Constantin, Genève