Minting Proof Coins
Proof coins are minted by using exceptionally well-crafted dies -- the piece used to impart the image on the coin. These dies are washed several times and then polished in order to give proof coins their mirror-like finish. The actual process of minting a proof coin is slower than minting regular coins. This is done to ensure that proof coins have the most pronounced details.
Cameo Proof Coins
A cameo proof coin is an extremely well-struck, reflective proof coin with a frosted look on the highest parts of the design. Cameo proof coins were very rare in the 1800s and most of the 1900s, but as minting processes became more technically advanced in the late 1970s, cameo quality proof coins became more common.
Lincoln Cameo Proofs
Cameo proof Lincoln cents have exceptional detail and a brilliant, mirror-like background. The hairs and lines on Lincoln's face are especially eminent on a cameo proof Lincoln cent, as are the creases in Lincoln's suit and his bow tie. The contrast between the frosted raised portion of the coin and the reflective background is obvious on cameo proofs. This contrast is one of the things that makes cameo proofs attractive to coin collectors. Cameo proof Lincoln cents are worth more than regular proof Lincoln cents.
Deep Cameo
Deep cameo is a term used to describe an extremely strong and obvious cameo effect. These coins are worth more than standard cameo proof coins. A Lincoln cent that's designated a deep cameo is even more physically appealing than a standard cameo. The frosting on the high points of the coin -- Lincoln's hair and suit -- is in greater contrast to the background than on a standard cameo.