Unique Swiss 20 Carat gold single handed dress watch Circa 1950

Gold open faced with special diamond set dial
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Exceptional, extremely fine and unique, large, 20 Carat yellow gold, keyless dress watch with a single hand, circa 1950. With a special champleve enamel and diamond set dial. Accompanied by the original Vacheron & Constantin fitted box and copy of the Vacheron work ledger. The Only Watch with Single Hand ever Made by Vacheron & Constantin Vacheron & Constantin, Genève. Sold to H. Thommeu, Bruxelles on February 7, 1950 for 2640 Francs.
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The back with royal blue champleve enamel “C” and engraved “Encore un Instant et Tous T’Auront Oublié, Encore un Instant et Tu Auras Tout Oublié” hinged U shaped bow, winding crown set with a cabochon sapphire. Brushed silver dial with royal blue champleve enamel chapter ring, brilliant cut diamond set hour indexes and baguette diamond quarter hour indexes in platinum settings, inner engraved indexes and painted 10 minute divisions, inscribed “Utere Non Reditura”. Single gold epee hand with ruby jewel centre. An ultra thin, rhodium plated movement, oeil de perdrix decoration, 18 jewels, straight line lever escapement, cut bimetallic compensation balance, blued steel flat balance spring, index regulator. Dial, case and movement signed.
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Diameter: 54 mm
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Signed: Vacheron & Constantin  Genève
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The case is slightly chipped.
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The present watch is unique in the output of Vacheron & Constantin and is the only watch made by them with a single hand. It was evidently made as a special order and in fact, the work ledger for this watch states that the diamonds for the dial were provided by the client. The inscription on the dial translates as: “Use the hour, it will not come again”.