A shot in dark....! The fineness mark gives some clues. The per-millage value tells us that it is made not earlier than on the latter half of 19th century or later, The 830S fineness and S indicate Denmark or Norway. Nothing suitable in Denmark, but in Norway I found I.W., Ivar World, active in Oslo 1917-1930. Is it Ivar or not, I cannot tell. That is all I can come up with.