I'm going to put a suggestion out there for you to consider. It sounds to me that your gf is a traditionalist when it comes to diamonds, and she is very lucky to have a bf who is taking such care in this choice. my suggestion is the classic Tiffany diamond ring, diamond only, plain band. If you really research it you will find that you would be able to purchase a larger diamond for her in this classic design compared to the cost of the other rings you are looking at. I have Never known a girl in my life who did not Love this setting especially if it's larger than she expected! If you look at the Tiffany Metro wedding band ths would make a lovely full Circle eternity band at a very affordable price and give a totally classic look that she will get tons of compliments on. As she has left this up to you entirely, this classic choice is NEVER wrong. Old saying...because I'm old...when in doubt about diamond rings always go bigger and stay classic. Spend your hard earned money on the biggest diamond you can afford and spend your money in the wedding band on the smaller stones. Beautiful now, beautiful always.She can wear her diamond eternity metro band to work for lots of bling and it wont interfere with her work.You will be a hero! My opinion for what it's worth. Good Luck!