Hi, What are your opinions on black tarnish on silver coins? Is it good or bad to have? Here is an example from the internet: I know that this kind of tarnish can be created artificially with the help of eggs. Some acid-cleaned coins also produce this black tarnish (I believe it's a reaction to sulfur exposure). What I'm asking: is this black tarnish a good thing? Should you or should you not collect coins with this black patina? It seems like this doesn't add much to the coins' value at all. Should these coins be cleaned? With what? The yellowish silver tarnish is a lot more beautiful, but quite many coins do have this black tarnish (which I do like to some extent, but the yellowish one is far better looking).