Newsfeeds are consistently filled with new hair-color ideas, and most of the time, it's a celebrity or influencer serving up the stellar looks. Celebrities (and their stylists) are at the forefront of many major trends we've seen over time and now, we're seeing blue hair everywhere. From icy, to seafoam, to cobalt, and anywhere in between, it appears blue is the color of 2018. RIhanna rocked a practical deep blue while Hillary Duff went with textured nearly green waves..