I went Blue Nile, and my wife loved the ring.
In hindsight though, wouldn't it be wonderful if you could just give her a total stock fund with the money and let her know how much it should be worth when you hit your 25th anniversary. At that point she can buy a ring that's twice as big, and not worry about the cost.
The trick is not getting caught up in the "I married a cheap son of a bitch" syndrome.
I bit the bullet, bought the biggest stone I could emotionally handle, and wrote it off as the most important investment in my life.
My brother, on the other hand, bought several, and never of them ended up in a marriage. In his case, maybe the stock fund would have worked better...