Is settling for Cubic Zirconia engagement ring a mistake?

well my boyfriend and I have been living together for 3 years now and I have decided to pop the question on a very tight budget I bought him the titanium ring that he has been lusting over since I first met him and now all thats left is getting my ring. I've never been one to spend money on anything really( I work at a non profit don't make much almost every item in my life is used and boughten for dirt cheap) and bought myself a cz engagement set and now all I can think about about is did I let my self down by not getting a dimiond? When I propose to him he will get a brand new playstation 3 the new batman game and his ring...I will get my cz set...I love him more than the world but I feel Like I cheated my self but at the same time I would really hate to spend all that money on a stupid rock.