Credit: Courtesy of Tiffany and Co.

If you've long dreamed of designing your own engagement ring (or, perhaps, have begun to suspect that you'll have to), get excited: As of today, Tiffany's has an app for that. The iconic jeweler has taken ring shopping mobile, making it easier than ever for you and your groom-to-be to pick out your dream rock. Browse by stone, setting, and style; there's even a feature that allows you to determine your exact size by placing a ring that fits onto an "alignment circle" on the iPhone's face. And you can share your favorites with your buddies and your boyfriend, perhaps ensuring that you'll be pleasantly (un)surprised when he finally does pop the question.