The Sheldon Grading System
The Sheldon Grading System or the Sheldon Scale, which runs from 0 to 70, is the brainchild of renowned numismatic Dr. William Herbert Sheldon. He developed it in 1948 as an attempt to standardize coin grading, especially as far as the grading of large United States cents go, although it is used to grade a far greater selection of coins today.
The better the condition of a coin, the closer the value afforded to it according to the Sheldon Scale will be to 70, and the worse the condition of a coin, the closer the relevant value will be to 0. Thus, 0 reflects the worst possible condition a coin can be in as denoted by the Sheldon Scale, while 70 denotes the best possible condition a coin can be in as denoted by the mentioned scale or coin grading system.