Use "I do now I don't" (.com). I have no affiliation with them whatsoever but I bought the engagement ring for my fiance from them.....it's basically an online marketplace for used engagement rings/jewelery. I was able to contact the seller of the ring I bought, negotiate, and then purchase through the site. IDNID receives the rings from the seller, verifies the authenticity, and if everything is good they ship to the buyer with the official certification (American Geological Institute)