
I've finally got around to restocking my supply of 3M anti-tarnish strips. This paper is treated with activated charcoal to protect silver, nickel, copper, bronze, brass, tin, and gold by absorbing sulfides and other pollutants that naturally occur in the air and thereby prevent tarnish from forming.
They won't clean something that's already become tarnished, but a piece in a jewelry box will keep jewelry tarnish-free for about 6 months. They're non-toxic, leave no stains or residue, and emit no gases or fumes. They work nicely for silverware chests, too.
$5 for a pack of 10 strips in my Etsy shop.