English silver verge watch with extremely rare movement Circa 1750

Silver and tortoiseshell watch decorated with stones
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A verge watch with extremely rare movement made by James Rousseau in London, England, circa 1750. Both cases of this open faced watch were made later especially for the movement. The enamel dial has Roman hour numerals, outer Arabic five minute numerals and fine steel hands. The movement of greatest rarity has silver decorations, is set with stones and the cock and pillars are probably all with tourmalines. Movement signed.
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Diameter: 50 mm
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Weight: 97 g
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Signed: Ja. Rousseau London
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No comparable verge movement from this period with such decoration is known. This may be a unique piece. Unfortunately, the original, possibly precious, case has disappeared.
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James Rousseau
Unfortunately, the trade literature holds hardly any information on James Rousseau except for noting that he was active in London between 1743 and 1761. It is likely, however, that he came from the prestigious Rousseau watchmaking dynasty in Geneva.