AU-50 (About Uncirculated) - very light wear on the highest points; still has at least half of the original mint luster ...
AU-50 (About Uncirculated) - Sharp legends and devices show only a trace of wear on the highest points. There must be some remaining mint luster.
AU-50 This is for "About Uncirculated" (the grade) and "50" (the numerical designation of that grade). Also called "Almost Uncirculated-50." This is the lowest of the four AU grades, with the others being AU53, AU55, and AU58.
662 1867 AU-50. Lustrous and frosty medium gold with plenty of prooflike reflectivity in the recessed areas. Some scattered field marks are noted for accuracy.
AU-50: 50% of the original surface should show at least.
AU-55: Most of the original surface shows. (I mean the flowlines, die lines and other surface attributes, NOT mint red.) Essentially full diamonds.
AU-58: A Mint State coin with a trace of wear.
1912D, AU-50, $390.00
1914-P, ANACS VF-25, key date, with considerable luster, probably weakly struck, $555.00
1915-D, AU, $310.00 ...
AU coins come in AU-50, AU-55 and AU-58. As a novice, you probably won't be able to tell the difference between AU and Unc coins. I know I have trouble a lot of the time.
About Uncirculated (AU-50)
Obverse: Besides wear, the presence of some luster is required for this grade. Very light wear will show on tips of leaves and on cross and shield. Reverse: Light wear on number and trace of wear on stars.
For example, Choice AU-55 represents an especially select About Uncirculated coin (typical About Uncirculated being AU-50).
About Uncirculated (AU-50)
There are traces of wear on most of the higher areas of the designs and considerable disruption is seen in the larger fields. At least half of the original mint luster is present.
Choice / Extremely Fine (EF-45) ...
Some experts feel that AU-53 is a superfluous grade and, therefore, the difference between a coin graded AU-50 and AU-53 is hard to describe.
But these were heavily saved by collectors and dealers, and today the 1931-S brings a very nominal price (about $24 in AU-50), considering its rarity.
About Uncirculated (AU-50) - Has traces of light wear on many of the high points. At least half of the mint luster is still present.
About Uncirculated - 50. Abbreviation: AU-50 Coins in this grade have traces of wear on nearly all of the high areas on the coin. At least half of the original mint luster remains.
Almost/About Uncirculated (AU-50)
Very light wear. There is about half of the original color.
Choice About Uncirculated (AU-55) ...
A grade that is usually one level higher than the market grade; refers to a coin that is "pushed" a grade, such as an EF/AU coin (corresponding to 45+) sold as AU-50.
A synonym for regular strike or business strike.
An adjective used to describe an above average specimen of a given grade. For instance, Choice EF-45 represents a coin above the typical EF-40, but still below AU-50.
Choice (2) ...
An adjective used to describe an especially select specimen of a given grade. For example, Choice AU-55 represents an especially select About Uncirculated coin (typical About Uncirculated being AU-50).
chop mark ...
In another example, from my specialty Charlotte Gold, an 1838-C half eagle trends for $5750 in EF-45 but jumps to $14,500 in AU-50.
Of course, some proof coins are impossible to distinguish as proofs once they are worn beyond a certain point. Therefore, circulated proofs may also be graded by their circulated grade level (i.e.. VF-20 or AU-50), ...
See also: Mint, Coin, Grade, Marks, Struck