I would steer clear of the diamond cellar, they were by far the most expensive place I visited. One of my buddies paid about 5k more for his wife's ring than I did and it is considerably less carats than my wife's ring, and my wife's ring is a better cut, clarity, and color.
BTW, if you are looking to buy a ring, start reading up on the 3C's.... http://www.bluenile.com is your friend.... there is a lot to be learned.