“Cool and neutral skin tones can wear most cool-toned blue hair colors, while warmer skin tones usually look the most natural with purple and ... These blue highlights look especially stunning ...

Blue shampoo. According to Emily Claire, a Davines colorist at Rob Petoom, cobalt-colored formulas are more effective than their purple counterparts for maintaining highlights on darker hair.

Depending on your highlights and undertones ... navy blue and charcoal gray. Black hair looks amazing when teamed up with fire-engine red, cobalt blue or royal purple. Redheads look fabulous ...