Throughout history, the fanciest things have been used as currency, from seashells to cattle. So it would seem that the advent of coins would bring monetary circulation to uniformity. Coinage could be limited to gold and silver for large denominations and a few alloys for small change money.
But gradually, precious metals went out of circulation and gave way to cheap aluminum or copper coins. Then, everything changed with the heyday of collectible numismatics. Money not for circulation but for collectors brought back the fashion for coins that are silver and gold. Mints began to produce new coins from unusual metals or add fancy inserts to attract collectors.