French three tone 18K gold repeating watch Circa 1780

Gold open faced keyless watch with quarter repeater
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A fine French 18 carat three tone gold open faced pocket watch with quarter repeating complication made by Ferdinand Berthoud in Paris, circa 1780. It has a mechanical crown winding cylinder movement with a quarter repeater mechanism striking on a gong and a tact system activated by pushing the pendant, signed Ferdinand Berthoud. The white enamel dial shows black Roman numerals for the hours, an outer minute track with Arabic five minute numerals, and ornate fleur de lis hands. The timepiece is housed in an elaborately chased and engraved round 18 carat solid three tone gold open faced case. The reverse side is centred with a green enamel medallion surrounded by rose cut diamonds and topped with a diamond set decorative bow, a diamond set bezel, and an internal metal resonance protective cuvette.
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Diameter: 38 mm
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Weight: 56.4 g
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Signed: Ferdinand Berthoud Paris