Swiss gold dress watch with American digital calendar Circa 1951

Gold watch with calendar and moon phases
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An extremely fine Swiss 18 carat yellow gold open faced keyless lever dress watch, circa 1951. With linear digital perpetual calendar and moon phases. A modern dress watch with a concave bezel, polished and brushed, correctors on the flat band, inverted U shaped bow. Brushed silver dial, applied yellow gold faceted baton indexes, outer minute divisions, aperture at 12 o’clock for the digital display of days of the week, months and date, aperture at 6 for phases of the moon concentric with subsidiary seconds and yellow gold dauphine hands. Rhodium plated movement, Geneva striping decoration, 18 jewels, straight line lever escapement, cut bimetallic compensation balance adjusted to heat, cold, isochronism and five positions, self compensating blued steel Breguet balance spring, swan neck micrometric regulator. Dial, case and movement signed.
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Diameter: 46 mm
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Signed: Patek Philippe  Genève
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Accompanied by the Extract from the Archives.
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Reference 725 and the nearly identical reference 725/2 were in production from 1940 until around 1964. To date, less than 20 examples of this model are known to have survived. The reference 725 is the scarcer of the two references. The difference is that the calendar aperture on this model has rounded ends instead of square ends. The watch with the ascending number to the present watch, 931099, was sold at Christie’s, Geneva, November 15, 2010, lot 347. 

The linear digital calendar or so-called American (perpetual) calendar is a calendar in which the date is displayed in a single linear aperture, allowing for a legible dial to be read at a glance. This type of display was invented in the early Art Deco period and is most often found in watches destined for the Anglo-American market. This kind of calendar became popular once again after the Second World War.