The 2nd Edition of "PCGS Coin Grading" is an excellent reference. It is critical and required reading for beginning and advanced coin collectors. As I am the author of 7 coin books since 1977, I appreciate the difficulty of attempting to explain the subtle and challenging differences between "a few minor marks in the main focal area" (MS65 grading standards, page 28) and "a few minor marks or one or two significant marks with hairlines" (MS64 grading standards, same page). As a complete reference to the condition (grade) of all U.S. coins, this book does an excellent job. However, as noted on page 7, with reference to the 11 grades of Mint State coins (MS60 to MS70): "It would be desirable to have more space for them on the grading spectrum to reflect their degrees of difference more precisely." This is why I am now writing a new book about Precision Coin Grading that will supplement the PCGS Coin Grading guide by explaining how to determine the "decimal point grade" of your coins. (MS64.5, MS65.8, MS66.3, etc.) In today's market, there can often be a price difference of hundreds or even thousands of dollars between a "just made it MS65" and a "just missed MS66." (MS65.1 vs. MS65.9.) Whether you are buying or selling coins for personal enjoyment or investment, collectors need to know whether they should consider upgrading a coin of "the same grade" (like snowflakes, no two MS65 coins are absolutely identical.) You also need to know if you have a "high end" or "PQ" (premium quality) specimen of a numerically grade coin, from Carson City Silver Dollars to U.S. Commems to St. Gaudens Double Eagles. Rare coin expert Jim Halperin has also attempted to address this issue. I've known both Jim and David Hall since the 1970's. Both are brilliant numismatists who have made valuable contributions to the hobby. Coin grading will always be an art as well as a science, and the 5 critical grading factors (surface, strike, color, marks and eye appeal) may never be determined by a computer, as my good friend Jim suggests. In the meanwhile, the more you know, and the more you learn, the better. As a tool to educate collectors about coin grading, The PCGS Coin Grading guide should really have better photos. Fortunately, many such photos are available on the websites of both PCGS and Heritage. If you don't own this great coin book, and you plan to spend more than $100 on coin collecting in your lifetime, buy this book immediately!