It's been called Blackberry Bling if worn on the thumbnail or simply an accent nail if on any of the other remaining digits. What is it? The act of painting one of your nails a different colour from the other four on each hand (or foot). Seen on the red carpet and at fashion week this season, it looks like the mainstream has started to accept (or at least absorb) some of the kookier nail trends being dished up over the last year. Now I'm not sure the childhood obsession with painting all your nails a different colour will resurface, but this subdued nail schizophrenia could be the way forward. And why not? You can do it with incredibly different shades/patterns or simply different weights of the same hue for a more minimalist COS-style look.