Swiss gold and enamel decorative ultra thin watch Circa 1790

Elegant pocket watch with open faced by Jacques Coulin & Amy Bry
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An elegant, decorative, key winding, ultra thin, large Directoire Swiss pocket watch, circa 1790.
Round-shaped, yellow gold and enamel case.Royal blue flinqué enamel (translucent enamel over guilloché engine-turning) case back with a neoclassical décor of paillons depicting a vase of flowers inside a vertical oval frame surrounded by friezes; invisible hinges. Enamel dial with Arabic radial hours, outer minutes track with Arabic five minutes numerals, and gold beetle & poker hands. Full plate, gilded brass movement with going barrel, cylinder escapement (brass wheel), monometallic balance (brass), and blued steel flat hairspring. Dial and movement signed.
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Diameter: 57.5 mm
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Signed: Jaqs. Coulin & Amy Bry
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Jacques Coulin & Amy Bry, Geneva Jacques Coulin (1744-1812), Amy Bry (1750-1830) and Jean Flournoy (1727-1811) were associates in Geneva between 1782 to 1799.
This watch is fitted with an extra flat movement, the calibre with going barrel, directly derived from the works of Jean-Antoine Lépine (1720-1814), of which various examples are known (with cylinder or virgule escapement) made circa 1785-1795 by himself and other Parisian watchmakers such as André Hessen (1775-?), Dieudonné Kinable († 1815), Jean Gregson (1776-1790), Gustave Adolphe Adamson (c.1747-aft.1813), Jean-Hilaire Bassereau (1743-1806), etc. This kind of calibre was developing at the same time in Geneva. This achievement allows the production of very elegant watches whose cases are built with invisible hinges. If these watches, in the latest fashion, are very popular with the aristocratic clientele of the time, they are also appreciated in the export markets like China.