Dutch indeed, for the Dutch (hall)marks see:
http://www.925-1000.com/forum/viewtopic.php?f=5&t=32028
Hi, the maker's mark
B&M above a
6 pointed star for: Willem
Baksteen & Cornelis Johannes
Middendorp, registered in Rotterdam 1861/1889.The date letter Gothic A for 1885. The Minerva head or assay office mark should show the regional assay office letter D for Rotterdam.
http://www.925-1000.com/forum/viewtopic.php?t=39483
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We also see the assayers mark for general use;
CH in a rectangle with cut corners for;
Chrétien
Hubert Emile Haenen, assayer for the assay offices Rotterdam, The Hague and Middelburg registered 1853/1891.
Peter.