Neon Blue Semi-Permanent Hair Colours To reach ultimate intensity, our brilliant Neon Blue illuminates hair with show-stopping cobalt tones and a shimmering purple tone. For the most vivid results, we recommend applying to pre-lightened hair. The colour on the pot is a simulation of the colour on a level 10. Soft, silky hair never goes out of style. That’s why all our colours contain a conditioning formula that nourishes hair from first application.