I should have noticed this before...
When I started collecting half dimes several years ago, I was still working primarily on my large cent set. My idea with the half dimes was to start with the collector era proofs, 1858-1873. But I ended up getting hooked on the larger, business strike set of Liberty Seated Half Dimes, and only infrequently added to the set of proofs.
Late last year, however, I did make one of those proof additions. It is a nice 1863 PR 66 Cameo, certified by PCGS - one of the last I got into the NGC registry. But there was something about it that I missed until just recently. My last two journals were about taking new pictures of my coins. The proof half dimes just had their turn. When examining the photos, I noticed something peculiar.
Some background: Starting in 1871, a defect appears on half dimes: The top of the D in UNITED is broken. According to Valentine, this occurs in all but one variety of 1871 (P), and all Philadelphia and San Francisco half dimes of 1872 and 1873. So the D must have become defective in the hub, but only after at least one 1871 (P) and the 1871-S obverse dies were made.
My 1863 proof half dime has the defective D. Judd lists patterns dated 1863 and 1864 that were probably struck in the early 1870s, consistent with use of the hub with the broken D. For 1863, only copper and aluminum patterns are listed, though Breen wrote that one silver example had been seen. My coin looks silver to me. I'll be having some more expert folks look at it in the near future.
On the one hand, I'm a little embarrassed that I did not notice the broken D earlier, or, if I did, that I did not note that it "should not" be on a 1863 half dime. On the other hand, I am disappointed in PCGS (in this case) for missing it too. They are supposed to be experts, after all. (The certification is for a garden variety 1863 proof.) Either way, I am very happy to have a rare item!