Macys.com has some nice stuff, every once in a while it gets really cheap, then other times its expensive.
I ordered jewelry for my gf from macys.com it worked out great, i also ordered from mondera.com and that worked out great too.
Stay away from overstock.com for jewelry -ive bought things from there that look like total crap when they arive (once i bought a pendant for my gf from there and the back was totally unfinished, parts of it looked like a hunk of solder)
Stay away from ebay, theres too much variance with it, its like buying expensive things at the flea market.