1830 10C Small 10C XF40 认证号36236636, PCGS号4517

Gordon Wrubel

Here is a tip in determining whether you have a Small or Medium 10C: Small has a round 0 in 10C that is smaller than the 1. Medium has a "football" shaped 0 that is the same size as the 1.

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Ron Guth

Eight varieties comprise the entire mintage of 1830 Dimes.  Seven of the varieties have what is known as a "Medium 10C"; the eighth variety has what is known as the "Small 10C."  The authors of the standard reference book assigned the number JR-2 to the Small 10C variety and assigned it Rarity 1 (common).  Their Condition Census includes "at least ten mint state pieces...", the finest of which is an "MS-67" in a 1982 ANA sale. 

The PCGS CoinFacts Condition Census includes seven Mint State pieces, the finest of which is a single MS-64.  For a coin that is supposedly so common, it is quite difficult to locate a Mint State example.

Sources and/or recommended reading:
Davis, David J. et. al. Early United States Dimes 1796-1837: A Reference Book of Their Types, Varieties and Rarity. Ypsilanti, MI: John Reich Collectors Society, 1984.