THE GUTH 100 POINT COIN GRADING SCALE SM
By Ron Guth
Executive Summary
Modern coin grading utilizes a 70 point scale developed by Dr. William Sheldon in 1948. Collectors and dealers in the United States coin market (and, in more recent years, the world) have used the Sheldon scale to evaluate scores of millions of coins, indicating the preference for (and advantages of) a numerical grading scale over an adjectival scale.
However, as popular as the Sheldon scale has become, it remains difficult to explain to consumers, it seems illogical in a 100 point world, and it has too few grading points at the top end.
The Guth 100 Point Coin Grading ScaleSM offers the following advantages over the old Sheldon scale and other alternative conversion methods

Easily understood 100 point grading scale

Adds 10 points to the MS/PR level, creating a total of 20 points from 80 to 100

Retains the familiar Sheldon grades from 1 to 58

Eliminates conflicts created by attempting a direct conversion of the Sheldon scale to 100 points
No decimals or rounding on conversion
Intermediate grades convert to whole numbers and require no rounding. 
Can be offered as an optional service

Creates opportunity to reevaluate and reholder previous submissions in the old 6070 range.
Easily understood 100 point grading scale Click here for a conversion chart
The Guth 100 Point Coin Grading ScaleSM is easy to explain and understand because it is based on a 100 point system already in use in many areas such as test results in schools, wine ratings, and even scoring in bouldering. Conversely, the 70 point coin grading scale is difficult to explain in a world where the 100 point system is so familiar. For instance, the current best coin grade of 70 would be considered a lowend “C” on homework or a test based on a 100 point scoring system.
Adds 10 points to the Mint State level, creating a total of 20 points from 80 to 100
Sheldon's grading scale is spread unevenly over a 70 point scale, creating too many points in the middle of the scale and not enough points at the top end. For instance, the Sheldon scale applies 20 points (2039) to the Very Fine grade, but only 11 points (6070) for Mint State, this being a reflection of the value/grade relationship for the coins surveyed by Sheldon in 1948. In the intervening years leading up to today, coin values rose dramatically on the high end, creating a situation where a single point at the Mint State level could represent a difference of hundreds or thousands of dollars. Today, most grading services utilize eleven points within the entire 6070 range to represent Mint State and Proof grades. Most proposals to expand the grading scale for Mint State and Proof coins include decimal, half point increments, or plus signs within the existing Sheldon scale. Clearly, an expansion of the scale for Mint State grades is both required and desired. To answer these shortfalls, the The Guth 100 Point Coin Grading ScaleSM moves Mint State and Proof grades to the 80100 point range, allowing for a doubling of Mint State and Proof grade points and eliminating any confusion with existing numerical grading.
Retains the familiar Sheldon grades from 1 to 58
The Guth 100 Point Coin Grading ScaleSM retains all of the familiar grades in the Sheldon scale from 1 to 58. Grades 60 to 70 (and their divisions) remain as placeholders but are replaced by grades 80100. In essence, the grades from 60 to 70 become optional but, in fact, any coins graded under the old 70 point Sheldon Scale remain viable until they are replaced with coins graded using the Guth 100 Point Coin Grading ScaleSM.
Eliminates conflicts created by attempting a direct conversion of the Sheldon scale to 100 points
No decimals or rounding on conversion
Intermediate grades convert to whole numbers and require no rounding
Mapping the old 70point Sheldon scale to a 100point scale by mathematical conversion (old grade x 100/70) results in odd, unfamiliar numbers, such as a new 43 for the old 30. Most points require rounding up or down after conversion, thus creating duplicate numbers upon rounding and requiring decimals to separate them. For example, both MS67 and MS67+ (or MS67.5) convert to 95.71 and 96.4, respectively, and both convert to 96 when rounded. Worse, a mathematical conversion to a 100point system conflicts directly with the old Sheldon scale, creating confusion and uncertainty in the marketplace. For instance, Sheldon’s old 30, which is considered Very Fine, becomes a new 43, which is considered Extremely Fine (and more valuable) under the old system. Such confusion and uncertainty may lead to abuses in the market when coins graded under a 100point conversion method are misrepresented as having been graded under the old Sheldon system. The Guth 100 Point Coin Grading ScaleSM eliminates any such confusion, allowing for a seamless implementation.
Can be offered as an optional service
The advantage of the Guth 100 Point Coin Grading ScaleSM is that it is offered with an additional tier level (80100) to prevent complete disruption of the old system. However, given a choice between a grade from 60 to 70 or from 80 to 100, collectors will most likely choose the latter, eventually rendering demand for the old system obsolete. By retaining the Sheldon Scale numbers 159 for the lesser quality coins and omitting the Sheldon Scale numbers for the greater quality coins, confusion in the market place is avoided. The 80100 range of the Guth 100 Point Coin Grading ScaleSM cannot be confused with the 6070 range of the Sheldon Scale, thus providing an enhanced and simplified method of grading higher quality coins.
Creates opportunity for grading services to reevaluate and reholder previous submissions in the old 6070 range
Submissions of previously graded and certified coins under the Guth 100 Point Coin Grading ScaleSM can be converted directly or reevaluated and given a new grade to correct past grading opinions and errors.
Implementation is easy
Implementation of the Guth 100 Point Coin Grading ScaleSM can be made easily. Conversions in software programs can be made programmatically by mapping the old Mint State and Proof grades to the new (i.e. 60 would become 80, 68+ would become 97, and so on). Consumers could be given a choice of grading under the old system or the Guth 100 Point Coin Grading ScaleSM, which can also be handled programmatically.
What happens to the millions of coins already graded?
Because there is no conflict between the old system and the Guth 100 Point Coin Grading ScaleSM, there is no imperative to convert. Coins in old holders could be converted slowly or quickly, depending on demand and the capabilities of the grading service, respectively. The tendency of collectors to choose a higher grade will fuel demand for the conversion.
Summary
The U.S. numismatic market has been searching for a way to a 100point grading scale for decades. The Guth 100 Point Coin Grading ScaleSM is a simple, yet elegant, solution that minimizes disruption to the existing market, creates a system that is easier to understand and explain, and facilitates participation in the exciting field of numismatics.
For additional information or licensing opportunities, contact Ron Guth at Expert Numismatic Services, Inc. at 8583498270