Many collectors are concentrating on obtaining high-grade modern Proof coins, mainly in the Proof 69 and 70 grades for registry sets or just to have near-perfect or perfect coins. Other collectors, however, have been seeking earlier Proof coins from the 19th and 20th centuries.

As a result, values for these earlier Proof coins have soared, many to the point where dealers are willing to pay full retail prices just to obtain a pleasing array of inventory to offer customers.

Because Proof coins were originally sold to collectors at premium prices, a large percentage of them have been preserved in higher than average condition.

However, some have tarnished or toned, have grown spots or other blemishes, or have been cleaned over the years.

Because of large price differences between low- and high-grade Proof coins, some people have tried to use artificial toning to cover up hairline scratches and cleaning-induced dull surfaces, by using chemicals, setting the coins in the sun or by others means that individuals known as "coin doctors" use to try to "improve" the looks of coins. So beware of artificially toned Proof coins.

If you buy third-party graded and encapsulated pieces rather than uncertified Proof coins, this danger is greatly reduced.

Obviously, coins that display unsightly tarnish or toning, or that have been cleaned or doctored, can be bought at much lower prices than the choice and gem quality pieces grading Proof 64 to Proof 67.

Often the overall look of a coin has a lot to do with its market price. This would include whether a Proof silver coin has a cameo or deep cameo finish, or is just a Proof with a consistent-looking surface.

Proof bronze coins, such as Indian and Lincoln cents, often sell for premiums when their colors are full, bright Mint red rather than darker or spotted.

In general, you can expect the 19th and 20th century Proof coins to sell for about 10 to 25 percent higher than our previous value listings for these coins. An across-the-board update is under way for these Proof coins. As each series is adjusted, values should reflect higher prices current in the market.