Thank you so much for all the responses. I completely agree that cut is king, and I have insisted on trying to get best cut possible. The stone I picked out is certified AGS 0 and is a H&A, a cut above. I guess it's not a hearts on fire or eight star diamond but I didn't think the premium was worth it.
What everyone has said makes me feel better about my decision. But I guess I still have some doubts. I didn't quite understand why this jeweler was so insistent on a G or better, because I saw a ring that was an "I" which looked beautiful to me, and I didn't really notice the color in it. And I completely agree that I will not be mounting the rock face down on white paper, but what DBM said makes sense to me too. I want this rock to take her breath away if possible. And I don't want to second-guess my decision or see the yellow in the rock when I look at it.
I guess one question I have is will a platinum setting bring out the yellow in a stone or is it just the opposite. I've heard conflicting things. The jeweler said that if I'm considering a platinum setting, it will gray out the stone and bring out the yellow even more. I've heard from my friends that platinum will actually make a stone look whiter. Maybe it doesn't make a difference, but does anyone have thoughts on what the setting will do to the perceived color. I'm getting a platinum setting.
Jonathan, I totally hear what you are saying and I agree that cut and fluorescence are the two factors that will neutralize color. But does setting make a difference too?
DBM: You said in tweezers and with fluorescent light a jeweler will be able to tell the difference between an F and an H. I agree because that's how I saw the stones, in tweezers (don't know if the light was fluorescent.) And I was able to see a slight difference. Not when I looked down on the stone from a distance because the white light reflected off it too much and all I could see were sparkles. But when I held it a bit closer and turned the stone in the tweezers I noticed a bit more yellow light bouncing off it. I guess that could have come from the jeweler's gold jewelry but who knows. I wonder though, will I be able to notice the difference when the stones are set? And I guess all things being equal, if you've tried to get an excellent/ideal cut, polish, symmetry, is the difference between a G and H enough to make you start your search all over again? Because I'm willing to do that to get the right stone.
Like I said, I'm very confused right now. The "I" that I saw mounted looked beautiful and it made me think maybe I was foolish for insisting on H over I. Am I being too silly for letting this self-interested jeweler mess with my head like this? Help!