The U.S. Mint issues proof coins on an annual basis, but these coins are available in different varieties. A silver proof coin is worth considerably more than a clad proof coin. There are differences between the two, and an easy way to tell them apart.
Clad Proof Coins
A clad proof is a coin made by "sandwiching" layers of different types of metals. Dimes, quarters, and half dollars are among coins made with this process, which includes a layer of copper sandwiched by a silver colored alloy of nickle and copper. The edge of the coin has a copper colored band that is easily visible.
Silver Proof Coins
Most silver proof coins are made of at least 90 percent silver with 10 percent copper mixed in. The coin is not produced in layers, as the metals are mixed together. The edge has a completely silver appearance, and does not have the copper ring of clad proof coins. The U.S. Mint also produces American Eagle proof coins, which contain 99.99 percent silver.
Silver proof coins will weigh more than clad proofs. For example, a silver proof quarter should weigh 6.3 grams while a clad version is only 5.7 grams.
Difference in Value
Silver proofs are more valuable than clad versions. For example, the U.S. Mint price for a 2009 clad proof set is $29.95, while the silver proof set sells for $52.95. Before you purchase any silver proofs being sold at discount prices, check them carefully; they may be clad proofs.
Check the Dates
There were no proof sets struck from 1965 to 1967, and only clad proof sets were issued from 1968 to 1991. The U.S. Mint issued silver proof sets up to 1964 and after 1992.