http://m.ebay.com/itm/1821-25C-Capped-Bust-Quarter-/221962548820?nav=SEARCH Sure looks like it to me. The date is way off. I also think they only used flat based 2's for the "25 C." in 1821 as well so...
It's a fake. The date is that typical Chinese garbage style. And for some reason @Markus1959 posted a capped half instead of a quarter.
Mind you, I'm still learning to detect fakes, but isn't that black hole below the date a typical warning sign? Correct me if I'm wrong.
Hard to say because the images are so blurry. I'm thinking it's just random crud/discoloration rather than something physical.
Markus, I probably am missing something... The ebay coin is a crude fake however the 1821 in this thread looks like a 100% genuine O-103 half dollar. Send it in to a TPGS. IMO it will come back as genuine.
I know it doesn't have a P mintmark, and it shouldn't. But even if Philadelphia used P mintmarks, the P would stand for Puyang, China.
Seller is light on experience, you have to ask him about shipping and there are no returns. Enough red flags for me whether the coin is real or not.