There are enough colours of the rainbow to go around — so when just one of them starts popping up on the heads of celebrities, influencers, and beauty lovers alike, you know it must be good. Lilac is the hue of the moment, with over 100,000 photos across Instagram showing variations ranging from lavender and dusky periwinkle to more saturated amethyst. The term "lilac hair" is also up 1,077% on Pinterest , making it one of the year's top trends — and it's only February.