Michael wrote:
Having never really collected certified coins, I would like to know
what is meant by the term cameo when used in the grading of both proof
and mint state coins?

Just to add a point: what has been said is correct for MODERN coins.
Also, as noted many Morgan Dollars have cameo and deep cameo features.
The Mint was forced to strike millions of these useless coins and they
went through hundreds of dies. New dies under adequate pressure
created the "cameo" appearance of a proof-like coin, though, of course,
the coins were NOT proofs.

Proofs -- by definition -- are created from multiple strikes with
polished dies on specially prepared planchets. Proofs probably go back
no farther than the late 1600s as rarities. As we would recognize
them, they are identifiable from records of the early 1800s and
forward.

The "matte proof" finish of the early 20th century, invented in France,
and briefly popular here, never has a cameo effect, by its very nature.

(If you go to the ANA website, www.money.org, and click on the dropdown
for Communications, you can select Numismatist, the monthly magazine.
In the 2005 Archives, the May issue has a cover story that I wrote
about Proof Double Eagles.)

Mike M.