I know this isn't what you asked, but from personal experience, I've found depending on what you're buying, it is worth going to the caribbean to buy jewelry. You might save enough to pay for your trip. Seriously.

Any jewelry store should have either a catalog or empty semi-mount settings you can choose from. Even Kays in the mall.

http://www.jewelryexchange.com/store.aspx?storeID=34&x=20&y=2

I have a ring I'd like to have re-set, and this will likely entail purchasing new diamonds.

Where in MoCo should I go?