Barber and Mercury dimes are perhaps some of the most difficult coins to turn into rings. You have very little metal to work with, only a fraction of metal compared to silver half dollars, as an example. The small silver dimes must be annealed several times during the folding process, or they will break. Also, on the initial fold, the coin must be straight, or a major wobble will more than likely occur. They are fun rings to make, just don't get in a hurry and remember to anneal several times, as they work harden much quicker than larger coins. Happy coin ring making!