All silver alloys are made from fine silver. The addition of copper to fine silver makes it more durable and lasting. Sterling silver is used widely for jewelry and elegant flatware. Sterling silver will slowly tarnish when exposed to air and moisture. The small amount of copper in the sterling silver alloy is principally responsible for the tarnish.
Pure silver tarnishes very little, but is too soft for jewelry without being alloyed.
During wear sterling silver will attain its natural patina finish, however it some times will turn black is one eat's alot of egg products due to the sulfur in the body. Coin silver is another common alloy of silver. Coin silver-tarnishes easier than sterling silver. However, the constant use of coins kept them clean of tarnish with a beautiful patina finish. Many people ask where the silver we use comes from.