Swiss gold open faced keyless winding pocket watch Circa 1925

Gold watch with Guillaume balance 
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A Swiss 18 carat gold open faced keyless pocket watch by Paul Ditisheim, La Chaux de Fonds, circa 1925. A polished, solid, plain case. White enamel dial with Bold Roman numerals, outer minute track, subsidiary at 6 and blued steel hands. A rhodium plated movement, Geneva striping decoration, 16 jewels, straight line lever escapement, brass invar Guillaume balance, Breguet Elinvar balance spring, index regulator. Dial, Case and Movement are signed.
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Diameter: 50 mm
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Signed: Paul Ditisheim Solvil  La Chaux de Fonds
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This watch represents the ultimate version of the popular line of pocket chronometers, Paul Ditisheim intended to develop with the “Solvil” tractemark. The first attempts were made with the Affix balance, patent No. 91169 from 31 August 1920 and 98234 from 25 August 1921, this model of Guillaume balance was finally adopted.