What this coin looks like (obverse, reverse, mint mark location, special features, etc.): There were a few major varieties of the 1830 Capped Bust silver dime. The first two varieties deal with the size of the words "10 C." on the reverse of the coin. The characters are roughly the same on both coins with the exception of the "0". In the large 10C version: The "0" lines up vertically with the "1" and both have roughly the same size relative to each other. In the small 10C version: The "0" is slightly shorter and smaller relative to the "1" and will not line up vertically to each other. The difference between the 1830 Small 10C vs Large 10C can be seen in the example image above.
In addition: there is also the 1830/29 overdate variety where the 1830 is stamped on top of the 1829 date. Very small parts of the "29" can be seen under the overlying "30" as depicted by the arrows in the example image of the coin below: