Extremely rare French 18K gold miniature ring watch Circa 1770

Gold verge ring watch with a paste-set gold key
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An extremely rare French 18K gold miniature ring watch with 13.5 mm verge movement and a paste-set gold key, circa 1770. Accompanied by a gold-tooled red Morocco trunk-form fitted box. Circular body with hinged bezel chased with foliage, polished and foliate chased band, glazed back, shank with pierced rococo decoration.  White enamel dial, radial Roman numerals, outer minute track and Arabic five-minute numerals, winding aperture between 3 and 4 o’clock and yellow gold arrow hands. A hinged, frosted gilt full plate movement with cylindrical pillars, fusee and chain, verge escapement, three-arm steel balance with flat balance spring, pierced and engraved foliate cock. Movement signed.
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Diameter: 19.5 mm
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Signed: J. Thierry  Paris
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Lacking elements on the movement and the hands are partially replaced.
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This ring watch contains one of the slightest watch movements of the 18th century with a diameter of 13.5 mm. Miniature watches have always been a challenge for watchmakers, who have vied with one another to produce ever-smaller mechanisms. The earliest known surviving example is a tiny gold and enamel clockwatch by an unknown German maker, circa 1610, which once belonged to Queen Elizabeth of Bohemia and was sold as part of the Harcourt Collection at Sotheby’s London in 1992.
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Ring Watchmakers have always been fascinated with the idea of fitting a watch into a ring. Only a few succeeded. In the early days, successful attempts finished on the fingers of Kings, Princes and prelates. In the Metropolitan Museum of Art, there is a very early ring watch, dated about 1560 and signed I.W. The Mantua archives contain a letter from James Widman to the Duke of Mantua concerning three ring watches, and quite possibly, one of them is the one in the Metropolitan Museum. In about 1650 Johan Ulrich Schmidt of Augsburg made a ring watch for the Elector Johann Friedrich. In 1764, the young John Arnold presented an extraordinary ring watch to King George III of England. It was a half-quarter repeater that was less than two centimetres in diameter and had 120 parts. The watch brought fame to Arnold and established him as a competent watchmaker. The Emperor of Russia offered Arnold double what George III had paid, for another such ring, but Arnold refused.