Coin grading is one of the most important things a collector must learn before going very far into the hobby. Coin grading is not only valuable to find the condition of your coins but also to make sure you’re buying or selling coins at a fair price based on their condition. Professional coin grading services, such as PCGS, NGC, and ANACS, have trained professionals to determine the grade, and thus, the value of your rare coin(s). Some coins are easy to grade, while others are much more difficult, for one reason or another. Often this involves the design of the coin, which may be unique to a specific series. This can also make determining if a coin is genuine difficult. These are some of the most difficult coins to grade, even for professionals who have been in the profession for many years. 

1.) Indian Head Quarter and Half Eagle 

This coin series, designed by Bella Lyon Pratt, comes in both quarter and half eagle denominations, so $2.50 and $5.00, respectively. What makes these coins so unique is the incuse design, where the main design of the coin is sunk beneath the field of the coin. Looking at most other coins, you will see that the design stands out above the field of the coin. Coin graders often use the portrait and relief to determine a coin’s grade. This is because this is the part of the coin that stands out and is prone to the most scratches, hairlines, dents, etc. Unfortunately, the sunken relief of the Indian Head Quarter and Half Eagle coins means graders have to look for scratches and hairlines on the field to determine the correct grade. Unless the coin has been heavily circulated, and Indian Head Quarter or Half Eagle should rarely have marks, scratches, or nicks in the design of the coin. 

2.) Classic US Coins 

US Coins minted in the earlier days of the US Mint can often be incredibly difficult to grade. The technology of the mint was sub-par at the time. The dies were often of extremely low quality, which makes grading these coins especially difficult. Due to the poor minting process and dies, a coin that just was released from the mint may be lacking many parts of the design and may appear, at first look, to be a circulated example, save for the mint luster. Additionally, planchets were also often of low-quality and caused many lamination errors and other types of errors, sometimes even making a coin without an error rarer than one with the error. Going along with the striking process, mint workers would often adjust the planchets before striking, to keep the weight and size of the coins more consistent. This would often show up in the coins after striking, which may cause a completely uncirculated example to have large, obvious scratches through the surface of the coin. The poor quality of the coins at this time also means that counterfeit coins can be a problem. It is difficult to tell whether a coin is counterfeit or not when the genuine example looks just as crudely and carelessly made as the counterfeit. 

3.) Standing Liberty Quarters 

The Standing Liberty Quarter was released in 1916. Until 1925, the coins had a major design flaw, the date was higher than the rim. As expected, this causes the date to be worn down long before any of the other details of a coin. This makes pre-1925 Standing Liberty Quarters incredibly difficult to grade. In 1925, the Mint changed the design of the coin to lower to date to decrease wear. Outside of “details” grades, or problem coins, there are really only two things needed for a coin to be graded – a visible date and mintmark. As long as the coin grader can determine what the coin is, the year, and the mintmark, it can be graded. Unfortunately, because of the high wear on the date, a Standing Liberty Quarter will often get a significantly lower grade than post-1925 equivalents, even if all other details are clear and sharp.