Hi Nata37,
it is Denmark!
Take a look:
townmark: Copenhagen 17??
assay master: Christopher Fabritius II, court juweler (1749-1787) - no 1755
master: B
randt Jonsen - no. B4-778
Brandt Jonsen was born in Island ca. 1719, buried 26.03.1777 – his widow Catherine Tronerup married Christian Werum, who took over the workshop.
Source:
Danske guld- og sølvsmedemærker før 1870, 4. udgave, revideret og udvidet af Henrik Jakobsen, Odense 2022, p. 25, 27, 108, 109
Regards
Silverstone