Swiss silver cased and enamel verge pocket watch Circa 1770

Silver open faced pocket watch
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Technically interesting, large verge watch with visible balance and an unusual movement by Jean-Marc Allamand a Genève,  circa 1770.
An original silver case, signed on the dome, very unusual and interesting gilt verge movement, original, signed enamel dial, visible balance, small defect near the winding stem, movement intact.
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Diameter: 57 mm
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Weight: 103 g
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Signed: Jean Marc Allamand  Genève