US clad dimes are not plated in the minting process. They are made from planchets that are made of clad material. The outside layers are mostly Nickel (90%Ni/10%Cu) and the interior layer is mostly copper (90%Cu/10%Ni). There is a book called the Error Coin Encyclopedia (The plaid book) which is a good read. It describes error coin definitions and the minting process. If you do not have the book then see how cheaply you can find a copy on the used market.
Another good reason to have a small scale. A dime on copper core should be slightly less than 1.5 grams.
