Lambertus Michaalis Thone, recorded 1781-1810, originally from Lige, became a citizen of Amsterdam in 1781, and worked with his son from about 1800 (Thone & Zoon).
Cf. a similar pair of pistols in the H.L. Visser Collection (HV-216/217) described and illustrated in J.P. Puype, The Visser Collection, vol. 1, part 2, pp. 424-7.