With this solution acting as an electrolite and the ring as a
cathode, a dissimilar metal like a hanging hook or another ring
could act as an anode, plating the silver out of solution like a
pickle pot with saturated pickle and a steel tool.
This does seem the most plausible and among my first reactions(pardon
the pun). I am puzzled though why a polishing didn't remove it. It
was cool though to see the white just disappear when it hit X
I use a covered quart plastic container for the solution immersed in
the main tank, to keep ammonia smell down. There's plenty of room so
I may start using two containers dedicated to silver/gold. Maybe I
can find a suitable plastic hook.
It would be interesting to see if I can duplicate the reaction on