Mark Cooper Trading as M. Has been a front-runner in the coin & bullion industry for over 30 years. Helped build some of the greatest collections of our time. In some cases, we even helped to sell them. Our customer service, fair pricing, and trustworthy service have made us a top rated company. Not a problem I. 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.