For example, check out the Owl Post Necklace available on Etsy:
Owl Post Necklace with Hogwarts Acceptance Letter, Wolfbird Studios (Etsy), $23
This particular Etsy shop has over a dozen Harry Potter-themed items include Golden Snitch rings and necklaces among other things. I'm not quite there in fan-world where I want to wear theme jewelry, but I can appreciate the design and craftsmanship that has gone into these items.
So, do you have your tickets yet?