DO NOT go to a mall chain. Find a local, reputable dealer. Learn about diamonds. It will save you thousands.
This...seriously. Go to a "higher-end" pawn shot that specializes in jewelry and at least look around. Then go to Jared and remember that metals are metals and gems are gems...new or old, there is no difference. You pay quite a premium for new, boutique jewelry; markup is absurd.
I bought my ring from http://www.bluenile.com. Also http://www.whiteflash.com is highly rated. They are located in Houston but by appointment only.
Buy online. Whiteflash is in Houston and I bought a ring through them. You can meet with them in person or email and they can help you find a good diamond for your budget. As said, don't go to any advertised Jared, Kay, or any of those. The markup is outrageous and you don't know what kind of diamond you are really getting (they'll list what they grade it as) unless you get it appraised. And chances are it will appraise for much less than you paid. Spence is a good place to go look and figure out what she wants if you can find a way to work that in. Excel diamonds, adiamor.com, bluenile.com, pricescope.com are all good resources to shop and research.
Cause it's tacky (and probably lousy deal too, I bet they rip your face off) on low grade merchandise, and shows that you just walked into the store at the mall and grabbed it. On saturday i was on a boat trip and saw a guy get down on one knee and bust out the Zales box - it was pretty cheesy. The best deals in jewelry come from either used/estate jewelry or backroom guys who cut you deals around the wholesale price etc. Got to know a guy who knows a guy...etc. I don't know any in H-town but I'm sure somebody here probably does.