Aw Sawbonz, and I thought we were gonna make it!!

LOL
Naw, you don't hurt my feelings by disagreeing, I totally respect your argument and supporting comments. You sound like a sweet, sensitive guy.
I never said that your girl should "demand" you buy her a ring she and her friends picked out. I just wrote that if she needs an opinion, (some might, some like myself prefer to shop for important things alone) bring a girlfriend who isn't pushy.
This also wasn't for the engagement ring (which I am with you, its fun when its a surprise), it was for the WEDDING RING.
Most guys are safe buying their girl a plain diamond solitaire to propose with, and then letting your wife to be have a voice in choosing the wedding set.
Thats kind of a classic approach, all my friends had that kind of proposal, my husband for me, even my dad did it for my stepmom. She took her late mothers ruby and re-set it in the original engagment setting. I am setting my birthstone in my old engagement setting. (which in gold, runs around $100 bucks...not a huge investment, and you get to spend your money on the stone, not the setting, for now)
Then you go onto http://www.tradeshop.com with your fiancee and let Ray the owner design on HECKUVA ring for you. Custom jobs cost a FRACTION of what the stores do. He posts all his client previews on the web and will make anything you desire. So you don't have to get 2 jobs to pay off the ring, and you have a few months before the wedding to have the diamond taken out of the solitaire and reset into the wedding setting. And you both got to choose.
Check out TradeShop's website, they guarantee everything until the cows come home and can design anything. I promise you wont be sorry or broke!!!!
One truth about marriage is, no matter how much you know your partner, you still need all 50 years of marriage to "know" your partner. It's the fun part!
so, recap:
buy loose diamond..(you'll know what she wants)
set in simple solitaire setting (cost effective and old-fasioned classic)
together pick out wedding settings or design matching sets! This can be fun!
You'll spend way less on the setting, get a better diamond, and she gets exactly what she has been dreaming of.