Sterling Silver Plated Pewter State of Maine Charm. Sterling Silver is the brightest of all precious metals. It has a shiny look and is not only beautiful, but durable. Sterling silver is an alloy of silver containing 92.5% of silver and 7.5% of other metals, usually copper. Sterling silver is more affordable than other precious metals. Our sterling silver jewelry is of very high quality and with proper care, should last a lifetime! Our pewter charms are lead free and made in the USA.