I'm not positive about jewelry per se, but the shops at the GF have lots of things, some were very pircey, but some things were reasonable, and it was a nice place to browse. A good break from the crowds. Not to be too stereotypical, but the guys sat and had a beverage, while the women had a look around. Everyone was happy. While it isn't my favorite themd hotel, it is very classy in there, so even the restrooms were nice. I'm pretty sure I saw some jewelry there.
They also had a little bit of jewelry at the gallery at the Boardwalk - the Wyland Gallery. Mainly it features Wyland Artwork (lots of whales and dolphins), but they also have other artists, and glass cases for collectables/jewelry. Not a discount store, by any means, but another beautiful place to browse for certain. It's kind of tucked away in the area behind the Flying Fish.
Then there are places to get 'kids' jewelry - I got a ring at the gift shop that's at the end of Stitch. The gift shop at the Swan had some cute things. There's also a big selection of costume jewelery at the POTC gift shop.