Weddings and Engagement

Sooo... I was talking to my mom yesterday about my boyfriend and we're both well aware that he wants to propose to me very soon. My mom is SUPER against diamonds and anything that resembles them. Some people may get why and cool cool but if you dont go watch the movie "Blood Diamond"on Netflix. She only wears a wedding band because of this. I'm not complaining or anything but im in the middle of watching this movie and also am kind of changing my mind about diaminds? But i dont just want a band i want somthing to show off. Any suggestions for a wedding or engagement ring that isnt diamond or too expensive?