Thin French gold and enamel verge pocket watch Circa 1780

Gold open faced verge watch  
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A thin French 18K gold and enamel open faced verge pocket watch, circa 1780.
Full plate movement, verge escapement, chain/fusee, three-arm brass balance.
White enamel dial with Arabic hours, outer minute divisions and Arabic quarter hours. The case back is decorated with cobalt blue enamel over engine turning, a central medallion with en grisaille painting on a pink-coloured ground depicting Cupid holding an arrow of love, surrounded by rose petals, the bezels on both sides with opalescent blue enamel pearls and gold paillon circles within a white border. Movement signed and numbered. The suffix Bt. almost certainly refers to the title par Brevet, meaning by warrant.
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Diameter: 51 mm
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Weight: 94 g
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Signed: Gregson Horr du Roy Paris
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Jean-Pierre Gregson originally came from England. In 1776 he was appointed watchmaker to the king in Paris. He was one of the first watchmakers of his time to use the Lépine calibre. In 1787 Gregson founded a watch company in Braille.