Nicole Richie Shows Off Her Rock

After confirming that she and longtime beau Joel Madden were engaged at last night's taping of The Late Show With David Letterman, Nicole Richie flaunted her stunning diamond engagement ring outside of the studio as photographers flashed away.

Nicole's already started planning her wedding, and Joel reportedly tweeted last night, "'Yep, I'm engaged. Very happy. Yeah we've been engaged for a while so your all kind of late on that. But thanks for the hoopla all the same," but the tweets have since been removed.