So I'm looking to find something preferably online that describes each grade. Mainly I have a slabbed capped bust half that is graded au53. I just want to find a site or something that defines au53. And really for future reference, all grades.
I'd suggest you take a look at the ol' mighty Red Book. At the start of the book, they describe each grade from high level; as an overview. Then for each coin, the author describes what the grades should look like for a given coin. It's certainly not verbose; just a few sentences, but should give you a good idea and certainly a good starting point.
Crack out a copy of ANA grading standards.... [edit to add] : I've got the 7th edition. Lots of color pics.
The most basic is something like this: https://www.pcgs.com/news/how-united-states-coins-are-graded I also find that a picture reference is incredibly useful. PCGS has a Photograde site that has pictures of every series in every grade: https://www.pcgs.com/photograde/ Now, if you want a book to lay this all out, someone has already mentioned the ANA grading guide - it has word descriptions and pictures of every series in every grade. There is a paper copy of Photograde as well. If you want a book to explain what the terms mean and how to evaluate them (strike, luster, wear, etc.).... I'm sure someone can recommend a really good book on that topic.
