As I see it, you have two choices. Offer her the smaller ring as a sort of starter-ring that she can get for now and you will replace on your 10-year anniversary (or something like that), or you can postpone getting married for quite a while longer. I think both options are good ones, and waiting might be good for you guys because you are really young to get married and met even younger.

If you love this woman so much, I assume this bratty meltdown is out of character for her. For one thing, you guys seem really really young to get married, which I think partly explains her really really immature response. She may, indeed, be a shallow, gold-digging bitch, as I assume many people are saying she is, but I can also see this as just the reaction of a very young woman not getting something she fantasized about for so so long.

If this is a sign of anything, it's not that you guys need to re-evaluate whether your relationship should exist, it's that you guys might be too young to get married. I expect the reason she's saying the other rings are ugly is because this is the way any young person reacts when they don't get what they want and you offer something else in its place. The bitterness of the disappointment is too strong, and if you offered her anything other than what she had her heart set on, she would reject it as horrible.

For a little perspective, in my urban, middle class circles, $6000 is pretty average price for an engagement ring (mine was $14 and I am perfectly happy with it, just letting you know that what she is saying is not completely insane). But these people getting married are in the late 20s and 30s and make much more money for longer than you have, so it is much less of their income as a percentage than that $2300 ring is for her.

Get her what you can afford now, with a promise of her dream ring later, or wait to get engaged. Alternately, you can wait even longer and spend all that money on a great romantic vacation.