Hello Nosferatu,
Regarding; Pletterij Nederhorst' and 'Curacao'; ship yard & builders & repair
http://books.google.nl/books/about/N_V_ ... edir_esc=y" onclick="window.open(this.href);return false;
You could start by cleaning the hallmarks perhaps with garlic, but from left to right;
1.) Makers mark ; A hammer between two Z for; Zaanlandse Zilversmederijen n.v./b.v., Haarlem & Amsterdam, mark used 1920/1990
Please browse link for more information;
http://www.925-1000.com/forum/viewtopic.php?f=5&t=28590" onclick="window.open(this.href);return false;
2.) The Dutch lion passant 2 for; silver 833/1000 or 83, 3% pure silver, mark used 1814-1953
3.) Minerva head, assay office mark with the letter A in its helmet for the regional assay office Amsterdam.
4.) Date letter S for 1928
Best,
Oel