This deal has ended.
Through 6/10, there is a rare coupon code for 10% off at best-of-breed online jeweler Blue Nile. They are the largest online jeweler, having sold over 50,000 engagement rings. They buy diamonds through the same wholesalers that Tiffany's does, but can sell for 35% less. As always, there is free FedEx, no sales tax and a fully guaranteed 30-day return policy.