Yes capital gains applies to physical items too. There's lots of information covering capital gains from people who hold gold and silver. And to answer your second question, no you can't ignore profits on the physical coin. Although being a simple brass coin, the actual value of it is going to be pretty low compared to the bitcoin on it. I would be careful on how you try to sell the coin as well. From what I remember, that operation was shut down by the government because they considered physically minted bitcoins something you needed a license to sell.