That's where my engagement ring is from. My DH did everything over the phone with a company his uncle deals with all the time, and he knew he could trust. The thing that he learned is that they'll take a diamond back if your GF doesn't like what you select for her. All I ever wanted was a 1 carat round diamond. He bought a 1.6 carat pear shaped stone. I never saw it. He started quizzing me one night, asking questions like, "what if it isn't perfectly round?" I told him that I'd be disappointed since he knew what I wanted. He told me that his mother liked it, so I told him to give that one to his mother and buy me the one that I want. I'm the one who has to wear it forever, so I should have what I want. He sent it back and got me a 1.1 carat round and it is just beautiful!
He never would have done things this way, if his uncle didn't have a relationship with the jeweler. You only buy diamonds a few times in your life and these people do it for a living. They know exactly what to look for and what they can charge for it. In April, we won't be returning to NY for my anniversary band, we'll be going to a local jeweler whom we've come to know and trust.
Good luck with your decision.