Postby blakstone » Wed Dec 28, 2011 12:52 am
Not French but Dutch, with the date letter "P" for 1824. The mark is actually "NB" with a heart above & crescent below, and was used by the widow of Amsterdam silversmith Willem Netelenbosch (1766-1820; Master 1781), whose shop she continued until 1826.
New Dutch maker's marks from 1814 were required to be of square outline, but makers were permitted to continue using their old lozenge-shaped marks which had been mandated under the French occupation. Presumably the widow Netelenbosch was allowed to use this variant of her husband's old mark - distinguished only by the addition of the crescent - by virtue of this exception.
Hope this helps!