Rare Swiss gold anti magnetic pocket watch Circa 1881

Gold open faced keyless pocket watch
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Rare anti magnetic pocket watch with gold balance, gold lever and palladium spiral by Patek Philippe with extract of the archives, circa 1881.
An 18 Carat roségold, dome inscribed: “made to special order not to magnetize” by Patek Philippe & Co. Genèva.
Patek Philippe case punch, extreme precision movement with solid golden moustache lever, massive golden balance, palladium spiral, escape wheel made of special bronze, Wolf’s toothing, enamel dial, blued steel hands, Roman numerals and a subsidiary dial.
This watch is extremely rare.
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Diameter: 47 mm
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Weight: 73.5 g
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Signed:  Patek Philippe, Genève
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Only a few of these anti magnetic pocket watches by Patek Philippe are known, which have been manufactured in a small series.
One similar watch with number 62051 is described and depicted in: Martin Huber & Alan Banbery “Patek Philippe”  with extract of the archives.