New 100-point grading scale unveiled

A new numerical grading scale was recently launched by award-winning author, researcher and numismatist Ron Guth, of California’s Expert Numismatic Services.

Dubbed the Guth 100-Point Coin Grading Scale, it aims to improve upon the 70-point grading scale, which is “difficult to explain and it does not provide enough grading points on the high end,” according to a statement issued by Expert Numismatic Services this September.

“The Guth 100-Point Coin Grading Scale leapfrogs over the old Mint State and Proof grades from 60 to 70 and creates 20 new Mint State and Proof grades from 80 to 100. The new system complements and integrates the old 70-point system, leaving the grades below 60 intact,” said Guth, former president of Professional Coin Grading Service (PCGS) as well as PCGS CoinFacts.

“My goal was to create a new system that could be implemented simply and easily in conjunction with the old. The rare coin market has used a 70-point system developed in 1948 by Dr. William Sheldon, originally for use with U.S. large cents minted from 1792 to 1814. In the 70 years since the Sheldon scale was developed, coin grading has changed dramatically.   Converting to a 100-point system is a logical and necessary next step.”

The biggest advantages of this new system, Guth said, are it “achieves the goal of a 100-point scale with minimal disruption to the existing 70-point Sheldon scale, it provides 20 whole numbers for Mint State and Proof grades, and it makes it easier to explain coin grading to current and potential collectors.”

There is a need for 20 grading points on Mint State and Proof coins because the current coin market “squeezes plus or half grades, known as split grades, into the 60 to 70 range.” Guth’s new scale assigns whole numbers to split grades and eliminates decimals, rounding and pluses.

A detailed explanation of the newly launched scale and a chart mapping the Sheldon 70-point scale to the Guth scale can be found at

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