Possibly unique Swiss pocket chronometer with calendar Circa 1870

Gold full hunter chronometer by Ekegrén 
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An absolute rare and possibly unique Swiss 18 carat gold hunting cased pocket chronometer with calendar, circa 1870. Very fine Geneva spring detent chronometer movement, wolf’s toothing. Cuvette inscribed Chronomètre H.R. Ekegrèn Genève. White enamel dial showing the days of the week and date, Roman hours, outer minute divisions, Arabic date and seconds, and blued steel hands. Case engraved, blanc cartouche on the front, the band with dots for reading, the back lid is rotatable, reading the time without opening the watch is possible by rotating the back lid, direct central connection to the movement. Case numbered, cuvette signed.
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Diameter: 53 mm
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Weight: 140 g
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Signed: H.R. Ekegrén Genève
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In 2005 this piece was sold for 43,700 Swiss Francs. 
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It is assumed that this watch, with the combination of a montre à tact, chronometer escapement and calendar, is a unique piece.
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Henri-Robert Ekegrén, 1823-1896, is regarded as one of the most important Geneva watchmakers of the 19th century.