Rare Swiss gold double sided calendar watch Circa 1875

Heavy gold hunting cased pocket watch
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Extremely rare, heavy double sided calendar watch by Courvoisier Jonais,
Chaux de Fonds, no. 20012, circa 1875.
An 18 carat gold, à goutte hunting cased, double sided fly spring mechanism, enamel dials on both sides, one side with small second, dial signed.
The other side with very rare full calendar, display of date, weekday and month as well as regulation scale, a dial with minimum cracks on the edge, otherwise very good condition.
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Diameter: 54 mm
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Weight: 162 g
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Signed:  Courvoisier Jonais  Chaux de Fonds
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Watches like this are extremely rare, only a few are known. The patent is from Jonais Courvoisier, Patented No. 122, 27 June 1871 and was also used by Girard Perregaux. According to our research, one similar watch was offered at auction for the last time in 1998, identical to this watch with number 20015 sold for CHF 9.200!