What do you do with an unused engagement ring anyway, after wedding falls through?

Financially speaking, recycling it for your own future purposes is the best way. You could have the diamond mounted in a new ring one day to alleviate the stigma of giving a ring meant for someone else. Otherwise most people just sell it on eBay or a pawn shop where you will be lucky to get 20-30% of what you paid for it. Typically the buyers will recycle it themselves and sell it as new.

Here is another option - a jeweler serves as the middleman, so the person buying it knows it is really what you advertise as:

http://www.idonowidont.com/how-it-works

You won't get what you paid for it - perhaps a bit more than half. Part of what you paid for wasn't the ring at all, but the mall rent and the national ad campaign.

Don't recycle this for another woman unless it's your mother. Very bad kharma, and anyone will see through the fact that you had it available. It's not an heirloom ring, and that makes it something left over from the other woman. Don't.

you are the guy right? so, if you are then you can either sell the ring on ebay or craigs list or pawn it or take it to a jewelry store which buys used jewelry...but you will get nothing near what you paid for it.

the best thing is to have the diamond removed, either save it for the next time around and put it in a new setting or have it set in a different piece of jewelry to give to your mother or someone and sell the setting for the precious metal price at one of those stores which says "we buy gold"

Some Jewelry Stores has estate jewelry.

You could see if you could sell or exchange the diamond for something for you.

Diamond is the expensive part of the ring.

You could have the diamond reset or made into an necklace for your mom or someone.

You can pawn it or ebay it. Just don't use it again.