The 1843 Dime has a mintage of over a million pieces, which makes it a fairly common coin. However, the number of certified examples is fairly low. This is consistent with other dates from the 1840s, though there are lower mintage dates with higher-than-expected survival rates. For instance, the 1843 has a much lower population of certified examples than the 1845-O (with less than a fourth of the mintage of the 1843). However, the comparison breaks down in Mint State, where there are substantially more of the 1843's than the 1845-O's. The best comparison can be made with the 1841 Dime, which has survived in almost identical amounts as the 1843 in both circulated and Mint State grades.
In Mint State, collectors are most likely to encounter an 1843 Dime in MS63 or MS64. Gem examples are rare, and the best examples are three PCGS-certified MS66's.