It's the bridge of the glasses, in case you need a hint.
Hey, here's another link to a beautiful song which has nothing to do with anything in regard to this picture. But its so lovely, you should listen to it. This version is by the late but wonderful Eva Cassidy. I first heard it sung by Jacob Moon, but there isn't a version of it by him on YouTube, and this one comes with a little CSI, à la Gil Grissom goodness. ;)
Eva Cassidy "I Know You By Heart"