What causes a coin to be thicker on 1 side than the other and is there any value in keeping coins with this issue?
If the coin is as-struck, it would have been struck on a tapered blank planchet, and it would carry a premium as an error coin. Can you provide photos showing what you are talking about?
Ok. So that might not necessarily be a tapered planchet. Looks like a high pressure strike on one side due to a slight misaligned die. That raised edge sometimes is referred to as a Finned Rim usually thicker than the opposite side. Not a major error but for me a keeper!
There are three possibilities, a tapered planchet, die faces not parallel, or simply one side struck up faster than the other side.
