Swiss/French rock crystal open faced keyless watch Circa 1925

Rock crystal, platinum and diamond set watch 
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A fine and rare Swiss/French rock crystal, platinum and diamond set open faced keyless pocket watch made by Cartier in Paris and the European Watch and Clock Co. in Le Sentier, circa 1925. Nickel lever movement with 19 jewels. Silvered, engine turned dial, the minute track with triangular five minute markers, skeletonized, diamond set Roman hour numerals and blued moon hands. A case of faceted rock crystal, and platinum band, pendant and bow. Dial signed Cartier, case numbered, movement signed European Watch and Clock Co. Swiss, the bow hand stamped with Cartier numbers.
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Diameter: 45 mm
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Signed: Cartier
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The European Watch and Clock Co. was established in the 1920s as a joint venture between Cartier and Edmund Jaeger of Jaeger-LeCoultre in Le Sentier, Switzerland.