You may find this site quite useful: http://www.gemphotography.com/
As for equipment, I would recommend searching the web for guides on how to build your own lightbox. You can build one way cheaper than the cost of buying one and you'll get nearly the same results. It's tough to say "this is the camera you should buy" because there are so many different things to consider when buying, but if you'll be shooting jewelry (or other small items) you'll want to invest in a macro lens. Buy a good sturdy tripod and do not go cheap on it!
If you don't already have a background in photography a lesson or three would be invaluable. You'll likely find that product photography is a different monster with issues you'll have to deal with that you don't normally see in other areas of photography.
Good luck!
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