As technology has improved, so has the quality and the consistency of coinage. Like coins weigh the same within minuscule amounts of a gram, their diameter is sufficiently exacting to be usable in vending machines, and the metal composition is precise enough for us to trust in the value of our money. The invention of the collar ensured coins would be perfectly round and allowed reeding, smooth, or lettered edges, all of which discourage counterfeiting. Technological innovation has come a long way, and it hasn't stopped yet.