My understanding is that it has to be silver, which means jewelry, but any kind of that should work. All metal armor and weaponry is iron based (it's past the bronze age...) and silver is a poor metal for those purposes.
This may mean a bit of hunting around: merchants sometimes carry silver jewelry, but 3.50 introduced jewelry in villages as well. It's not common, but it can be found (and I think village ones are tribal, which currently doesn't mean anything technically).
Edit:
Also, consider that when the quest text says "sauna stove" it actually means a sauna stove, not a PC made stove usable as a sauna for all other purposes, so I'd definitely expect "silver" to mean actual silver.