Hi Sebastian, Dutch solid silver, I recognize the Dutch Minerva head or assay office mark. Your images are not clear, the maker's mark could be
JM under a fish in a square. If so for
Johannes
Mulder, registered in Amsterdam 1845-1862. Please check for standard mark, the Dutch lion and a year letter.
Silversmith Johannes Mulder was born in Nijmegen in 1816 and married Helena Feij in Amsterdam in 1843. He worked as a silversmith in the period 1845 and 1862, large and small silver. He died at the age of only 46 in 1862.
For Dutch hallmarks see;
viewtopic.php?t=32028
Peter
Source:
Amsterdams Goud en Zilver - Jan Rudolph de Lorm