5VA / Violet Ash, What it is: For a perfectly cool tone without the brass, try Redken Color Fusion Hair Color. It’s a permanent dye that comes in the coolest tones you’ll find. Choose from shades like brown violet, ash violet, brown red, and more. What it does: When used with a quality developer, this permanent hair dye penetrates the hair shaft to deposit hair color molecules deep into the hair shaft. The results are true-to-tone and lasts up to 8 weeks. This hair color is formulated with C-LOCK technology that imparts a long-lasting cool tone to all of the collection's shades. What else you need to know: This hair color is great for you if you want to counteract some of the warm or brassy tones in your hair.