Knowing how to grade coins will assist you in making more informed buys & will also help in spotting the odd bargain, or knowing if the coin is over graded. What will assist further in grading is a good magnifier 4x, 6x,or 8x.Look at the coins circumference, to see if it is a well centered strike all the denticals(beads around edge of coin) should be well stuck & the edge should be free of nicks.
However not all uncirculated coins are perfectly centered, the ones that are perfectly centered as a rule are; specimen strikes, proof coins, mint sets & some of the coins made for circulation can be be perfect strikes.Especially the earlier coins made with a new working dye. As the dye will eventually wear & round of in places. Another factor is the bag markings or contact marks which are caused through coins clashing with each other in the coin making process as they are mass produced,dropped in large metal boxes then placed in bags of 500 depending on denomination may vary.these coins are still uncirculated with inclusions as mentioned .Other factors to consider are the lustre,fullness of strike & all round eye appeal of the coin.
Gem Uncirculated; A far superior coin with an almost perfect strike,should be perfect to the naked eye,but under magnification may have minute detracting marks,should have full mint lustre or enhancing pattina (natural toning).Unless coin is copper or bronze. full lustre or at least 75% is required to maintain this grade.
Choice Uncirculated; a very well struck coin with minor detail missing of the high points of the coin,may have some insignificant detracting marks.Overall a moderately well centred & well struck coin with much eye appeal.Copper & bronze coin require 50% lustre or better to maintain this category.
Uncirculated; this coin may show some weakness in the strike of the coin,& also have some detracting marks,such as bag marking this can be minimum to a moderate nature.Mint lustre should be present on coin however it may be subdued.This grade is highly desirable due to the absence of circulation wear on the coin.
About Uncirculated; This category is the same as above the coin must display very good eye appeal,but may diplay some wear on the high points of the coin,this must be minimal,very lightly circulated.
Extremely Fine; Light wear on the high points of the coin,may display a number of detracting marks(contact marks),but the coin as a whole must still have some lustre evident even if only around the ledgend of the coin.
Very Fine; Moderate wear with flat spots on the highest points of the coin,detracting marks & edge nicks may be present,but the coin should still be a nice example with all ledgends & features on the particular coin should be easilly visible to the naked eye.
Fine; As above with more flat spots visible & many scatches,detracting marks but the coin features are still fully visible except for all the high points should be well worn.
Very Good; A coin that has many flat spots, scratches & detracting marks.however the ledgend should all be visible still.
Good; Extremely worn coin showing an outline of the former design, with flat spots all over & even parts of the ledgend showing wear (flat) .
I hope this helps you understand coin grading a little better,if you have any questions or need further assistance please dont hesitate in e-mailing me,You can even send me a scan & I will do my best to grade your coin by picture. e-Bay user name: petezac