Your fork in the Filet or Thread pattern was made in Paris between 1 October 1768 and 18 November 1774, as indicated by the crowned A charge mark. The date letter is incomplete, but should be either a crowned E, F, G, H, I, K or L. The date letter and charge mark are stamped head to head, so you’d have to turn the fork in the opposite orientation to what you have shown to try to decipher the date letter. You also have a discharge mark of helmeted youth facing right, in use 1768-1774. Thus all marks are in concordance.
The maker is Charles-François Lautran, who first registered his mark of a crowned fleur-de-lys, two grains, initials CFL and as symbol a mitre on 29 March 1762. In 1766 he was listed as working on the Pont au Change, and he died 21 June 1777.
Hope this helps.
See Nocq, v. 3, p. 42.