Skip Fazzari delves into the complicated task of grading Proof coins, and narrows down the mystery to one major factor.
A majority of collectors are familiar with modern US Proof coins that are seen with highly reflective, mirror-like fields and frosty devices. While the Mint issued Proofs with other finishes in the past, for the sake of simplicity, I’ll deal with the mirror-surfaced examples here.
Proof coins are special in that they are carefully struck, more than once, on polished planchets in order to bring out the utmost beauty of each coin’s design. Proofs represent the high point of the minter’s art. As they leave the coining press, they are generally as perfect as humanly possible. While the Proof process represents a special method of manufacture, over time, the "Proof condition" has become regarded as a grade above Uncirculated.
Grading Proof coins has become more complicated over the years. More than forty years ago, any Proof coin with problems such as scratches, nicks, heavy hairlines or friction on its high points was simply considered to be an Impaired Proof. Today we make distinctions between the states of preservation of Proofs using the same 1–70 scale we use for other coins. Since a majority of Proof coins do not come into contact with other coins, bagmarks are rarely seen, so slightly different criteria are used to evaluate Proofs. Eye appeal is still the most important, but other factors include the amount of friction, spotting and hairlines present. Let’s consider each of these points.
Some Proofs, especially those from the 19th century, have a slight amount of friction on the highest parts of their designs, due to mishandling or cabinet friction. Grading services may allow a tiny amount of this type of friction before dropping the grade of a Proof into the lower ranges. You will rarely encounter any Proofs below the grade of About Uncirculated (PF 50–58), since they were special and rarely suffered the fate of our regular-issue circulating coinage.
Dark spots of corrosion and white "milk spots" are both detracting to the eye appeal of Proofs. A spot in the field will be more noticeable than a white spot on a frosty device. Spots are weighted similarly to the bagmarks found on Uncirculated coins. The number, location and size of the spots determine how much the grade is affected.
Hairlines from improper cleaning or mishandling are another criteria used to grade Proofs. A large number of heavy, microscopic scratches that are easy to see in the mirror field as the coin is tipped and rotated through the light will lower the coin’s grade. Hardly any hairlines should be visible on a Proof coin graded PF 67 or higher. A significant number of these microscopic scratches are allowed on PF 63 and below.
The Cameo condition of a Proof has become an added dimension to their overall eye appeal but is separated from the grade. "Cameo" is used to describe coins with significant contrast between a mirror field and frosty devices. While most modern Proof coins are seen with Heavy to Ultra Cameo contrast, pre-1970-dated coins are less common in Cameo Proof condition.
In the end, the overall eye appeal of a Proof coin will usually determine its grade within a point. Don’t let yourself get too preoccupied looking for tiny random spots or hairlines — it’s mostly the large patches that are considered offensive. Any noticeable defect will eliminate the coin from the elusive PF 70 grade.
This article previously featured in Numismatic News.