A diamond promise ring has many meanings, but they generally
means that the giver of the promise ring will be faithful to the
receiver of the promise ring.
What does it mean if a guy says he wants to go out with you some day?
It could mean that you have pestered him or have had sex, so he
gives a generic "some day" promise to you so you will leave him
alone. This is not something you can bank on. Someone who is truly
interested will have similar interests as you do and getting
together for a date will be definite.