Swiss 18k gold keyless pocket watch with black dial Circa 1940

Gold open faced lever watch 
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An extremely rare Swiss 18k gold keyless pocket watch with a black dial, circa 1940.
A solid, polished case with a black dial, dot indexes, outer minute divisions, subsidiary seconds and yellow gold Baton hands. A rhodium-plated movement, oeil-de-perdrix decoration, 17 jewels, straight-line lever escapement, monometallic compensation balance, blued steel Breguet balance spring, micrometre regulator. Dial, case and movement signed.
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Thickness: 10 mm
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Diameter: 44 mm
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Signed: Rolex  Swiss
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Some dents on the case and the dial is slightly oxidized.