OK, we know blue eyeliner sounds really wacky, but after seeing it on the likes of Jessica Biel, and now Cara Delevingne at the Giles show during London Fashion Week, we're seeing things differently. The blue and green eye makeup trend has been bubbling just below the surface for the past year, but we think 2014 is when it will finally hit the mainstream.

The key to the look is letting your makeup be all about the eyes -- after all, blue eyeliner is a pretty bold statement. We suggest going neutral (or none at all!) in the foundation, blush, and lip categories. Bold brows like Cara's, are, of course, accepted.

Again, since blue eyeliner isn't your everyday look, no worries if you don't want to shell out for the trend. We recommend sticking with a drugstore favorite like CoverGirl Liquiline Blast Eyeliner in Blue Boom for a way to try out the look without committing.