Swiss gilt-brass, enamel and paste-set pocket watch Circa 1780

Gilt-brass verge with the portrait of a lady
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A fine and rare Swiss gilt-brass, enamel and paste-set pair cased verge pocket watch, circa 1780. Outer case: two-body, the back with polychrome enamel portrait of a lady, paste-set frame, translucent imperial blue enamel border over circular engine-turning, the band engraved with a repeated pattern, front bezel set with pastes. Inner case: polished with a deep back. White enamel dial, radial Roman numerals, outer minute track with five-minute Arabic numerals and elaborate paste-set hands. A hinged frosted gilt full-plate movement with pentagonal baluster pillars, fusee and chain, verge escapement, brass balance with flat balance spring, single-footed cock with ruby-paste endstone. Dial and movement signed. 
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Diameter: 39 mm
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Signed: Bordier Genève
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The case is scratched and slightly chipped.