Sorry, have no connections for you in LA, but I can recommend a jeweler or two with great reputations here in Chicago. My family and extended family has done business with both for decades and are family owned and run over multiple generations. I am buying my gf's ring and diamond from one of them this weekend actually...
Hoffman Jeweler's in Highland Park, IL (just outside of Chicago). Richard Hoffman is the owner and full of integrity. I've educated myself a lot over the last few weeks both through this site and asking around and then even testing Richard with products I located elsewhere. His pricing is very, very fair. You can go to their web site at http://www.hoffmanjewelers.com
I am not profiting from this recommendation at all, he doesn't know I'm on this site. I truly happen to think the world of him and his store.
Then, Lester Lampert of Lester Lampert Jeweler's. He is in downtown Chicago and when you go to his web site, you will see, has an national, if not, international reputation of quality and design. He will be a bit higher end as far as his typical clientele and price, although he certainly could handle all size transactions. His web site is http://www.lesterlampert.com.
Good luck.
