GF - make no mistake about this . . . an engagement ain't about you and her - its about her sticking that ring in the face of every person she comes in contact with from that moment forward
A ring just makes it "real" for most people . . . prolly why the tradition has been around for eons . . .
I'm in the let her help pickin it out category . . . when she asks "What's the budget" say "Whatever you think is appropriate . . . but just remember if ya go crazy - it might cut into your "shoe money".