Fine Swiss gold and enamel open faced watch Circa 1920

Gold and enamel keyless watch 
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Very fine and rare Swiss thin, 18K gold and enamel keyless dress watch, circa 1920. Manual winding, 15 jewels, straight line lever escapement, cut bimetallic compensation balance.
Matte gilt dial, Breguet numerals, outer minute track, subsidiary seconds. Blued steel hands.
Back decorated with champlevé enamel in a “millefiori” type pattern on a black ground, bezel en suite, band and bow in champlevé enamel in a geometrical pattern, winding crown set with a cabochon sapphire.
Dial, case and movement signed by maker.
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Diameter: 43 mm
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Signed: Wegelin Geneva