What is the value of a copper US nickel?

All US nickels except the famous "war nickels" from WWII are made of 75% copper, but the remaining 25% of the alloy that's nickel is enough to give the coins a silvery color. The only way a nickel could appear copper in color is if it were tarnished, altered by exposure to chemicals, or plated as part of a high-school chemistry experiment (we made lots of them when we studied half-reactions!).

Regardless of the cause, it has no added value I'm afraid.