I keep a magnet close to my jewellery bench and check a damaged
chain with it - I have been caught with gold and silver plated
Nickel plating is also magnetic - and a real headache to repair.
It is rock hard, bad for files and sawblades, and when soldering
it throws up kind of bubbles, which turn into holes in the heavy
plating when you sand the piece. Also, it will copper plate the
piece when put into pickle (same as with iron). Cheerio, Markus