Rare Swiss 18K gold keyless Chronometro Gondolo Circa 1912

Gold open faced lever pocket watch
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A fine and rare Swiss, 18K gold, keyless Chronometro Gondolo, circa 1912. Made for Gondolo & Labouriau, Relojoeiros, Rio de Janeiro. An engine-turned case with polished borders. Hinged gold cuvette. White enamel dial with radial Roman numerals, outer minute track with five-minute Arabic numerals, and subsidiary seconds. Blue steel Breguet hands. A gilt brass movement, patented bridge calibre, 21 jewels, gold train, straight-line moustache lever escapement, cut bimetallic compensation balance with blued steel Breguet balance spring, Wilmot’s patented micrometric cam regulator. Dial, case, cuvette and movement signed.
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Diameter: 46 mm
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Signed: Patek, Philippe & Cie.  Genève