I recently acquired this piece that acid tested 900+ silver on the mesh portion and <700 or none at all on the clasp and chain.
I make out the hallmark RK which I believe is Robert Kraft from Germany, working between 1900 and 1940? That puts it in line with the general age of the item.
Can't find any information on the Kraft Alpacca or Gelotet, however. Is it strange for it not to be marked 925 somewhere?
Anyway, here is the hallmark and item in question.:

