Earth Friendly Wedding Rings:
Passing rings on from a loved family member can be a nice way to keep from adding to the damage already done to our earth. If you do buy new, find out where your diamonds and other gems and materials originally came from. Make sure they come from socially and environmentally responsible dealers. Work with a company like GreenKarat (www.greenkarat.com), who can ensure you that you are buying responsibly.
You may also want to look into moissanite, although I admit I don't know the impact creating these stones has on our environment.