Your snuff box of 800 standard silver gilt was made in Paris by Claude-Louis Jonquoy, working at 83 rue Quincampoix. Jonquoy first registered 1818-1819. This is his fifth mark with the symbol of an imperial crown, two crescents above, and one below. You have mistaken the crescents for initial C. His initials CJ are found to either side of the symbol. This fifth mark was registered 27 June 1835, erased 20 August 1846. As the Minerva head silver standard mark was introduced in 1838, you can date your box quite precisely from between 1838-1846. Jonquoy continued to work until 1849. His specialty was snuff boxes (la tabatière).
See Arminjon, v. I, no. 00709, p. 105.
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