In the 1950s, grading practices were radically different from what we have today. A coin's condition was described using simple adjectives such as "Extremely Fine" or "Uncirculated". Accordingly, numismatic references of those times conformed to the same set of adjectives to approximate retail coin values. Varying distinctions of Uncirculated (today's equivalent of MS-60, MS-61, etc) and Proof were recognized in some advertisements and auction bills by employing modifying descriptors such as "Brilliant Uncirculated" or "Choice Proof", for example. However, with no clear point of reference or consistency on how the modifying descriptors were invoked, most publishers resorted to listing values for only one "Uncirculated" grade and one "Proof" grade.

The 70-point numeric system (G-4, VG-8, etc.) in widespread use today was popularized by the American Numismatic Association in the late 1970s, an era when coin values were escalating dramatically, most notably for high quality specimens. Vague descriptors such as "Choice" and "Brilliant" were replaced by the more precise numerically determined grades. Thus, finely differentiated grades like MS-60, MS-63, and MS-65 eventually became commonplace, and by the late 1980s, the practice of assigning a numerical grade to indicate quality was universal (this does not imply the 70-point system eliminated grading inconsistencies, but it did help to stabilize the coin collecting hobby).

In February 1986, the ANA changed its grading interpretations to match the tightening standards demanded by the marketplace. This meant that many coins correctly graded as MS-65 in the early 1980s became MS-63 or less, so as to be consistent with the newly revised interpretation. Conversely, a coin graded after 1986 as MS-63 was about equal in quality to an MS-65 before 1986. Thus, the Mint State prices published in numismatic periodicals prior to 1986 are not directly comparable to those published later. The Coin Value Tables of this website relied heavily on periodicals from before 1986, but we did not attempt to compensate for the revised grading standards of 1986; we reported what we found. One must take this into account when studying trends for an MS-65 coin from, say, 1980 to the present. On the other hand, because of the dearth of Mint State price estimates published prior to 1986, more than 98% of the Coin Value Table data is not affected by anything mentioned in this paragraph!

The Coin Value Tables trend data for American Eagle gold coins reflect the historic availability of numeric grades to describe coins. For the 1950-1985 rows, the values in the "XF-40" column correspond to the "Extremely Fine" listing of those years, "AU-50" corresponds to "Almost Uncirculated", and so on. The "MS-60" column records the "Uncirculated" value reported during those same decades. Similarly, "PF-63" corresponds to simple "Proof" figures. Starting in the 1990 row, coin values strictly correspond to numeric grades grades. Furthermore, "Uncirculated" grades are broken down into "MS-60", "MS-63", "MS-64", "MS-65", "MS-66", and "MS-67", because by 1990 and later, this type of Uncirculated value data for American Eagle gold coins was readily available. Beginning in the 1990 row and onward, the "PF-63" through "PF-67" figures are listed for similar reasons.

For those interested, we have a coin grading section with more details on the evolution of grading coins.