Not an opinion ,just an observation. I have seen a number of dimes with the rim edge displaying the copper coloured edge....my guess wear or too thin a plated nickel surface or just plain wear likely from a coin machine sorter.
Nickel-plated steel
From 1968 to 1999, it was composed entirely of nickel, and since 2000, it has consisted of a steel core with plating composed of layers of nickel and copper.
Nickel-plated steel
From 1968 to 1999, it was composed entirely of nickel, and since 2000, it has consisted of a steel core with plating composed of layers of nickel and copper.


























