Check out yelp.com. There are a lot of reviews for places in the jewelry district. I've personally visited a lot of them but haven't bought (at least not yet). I've been to Eli's, IntaGems, Icing on the Ring, Balian & Sons, Diamond Center LA, PopGems, Gorgeous Jewelry by Chen, and Bridal Rings to look at white diamond e-rings.
Balian & Sons had the best prices and very beautiful and unique setting designs. If you aren't looking for the best bang for your buck, I would check out IOTR and maybe even IntaGems, even though I personally thought IntaGems' prices were a little steep; however their settings and designs are quite beautiful and I read they put high quality diamonds their settings. IOTR looks like an actual store while IntaGems is a little booth, so I ended up liking IOTR more. IOTR also had the best warranty - not only do they provide warranty for their settings, but for the center diamond too! Not a lot of places do that! I know both stores are very reputable, as are the other jewelry places I mentioned (I found all those places thanks to Yelp!)