Most of our coins are graded to the World Standard known as the’Sheldon Standard’ 1-70. (70 being top grade). MS stands for Mint State (Uncirculated) AU means Almost Uncirculated and PR or PF means Proof. Why is a certified coin a better investment? PCGS & NGC are the main two impartial Numismatic Grading Services in the world and is a guarantee that the coin is genuine and has been graded accurately and professionally. The sonically sealed solid plastic slab is individually numbered so that the details of the coin(s) can be verified on a central database, and is also tamperproof. Not a problem I.