I don’t understand the grading terminology. What does it mean when a coin is designated “PR63″? Is that good or bad? Is there an “ideal” rating? What is the highest rating?

Coins are typically graded using a scale of 1 to 70.  A score of "70" would mean the coin has a perfect strike and is mint, uncirculated condition.  A grade of "1", on the other hand, would indicate a coin in extremely poor condition--not only very worn, but possibly even damaged in some way.

The grade number is preceeded by various designations which further specify a coin's grade.  A “PR” designation means the coin is a “proof” which is a special type of strike for the collector market.  This special strike is achieved using a greater striking pressure along with a die that is more highly polished, typically with frosted surfaces giving the coin a more aesthetic appearance.

In addition to "PR", other grading designations include:

            G = Good; VG = Very Good; F = Fine; VF = Very Fine; XF = Extremely Fine

            AU = About Uncirculated; MS = Mint State (uncirculated but not "proof")

An "MS" designation is usually only seen on coins graded between 60-70.