MadPoet, I think the gesture is sweet, as I am sure your GF will as well.
As Demo said, he gave me a promise ring. It by no means we are not going to be engaged to be married. We are, that we are sure of. But we are not ready to make wedding plans, and are not ready to shop for an engagement ring. We will when the time is right, for not just both of us, but our children and our extended families as well. This is just the kind of instance where a promise ring is perfect.
I love this ring, i gaze at if often, remembering how he bestowed it upon me, and thinking of the incredible love it symbolizes. Best Wishes.