If you’re like us, when you go to the salon to get your hair dyed, you have a very specific color in mind. Especially if you are going blonde, getting highlights or trying ombré, maintaining the crucial ash hue is the name of the game. As such, every girl needs to have an effective violet shampoo in her beauty regime. The science behind it is quite simple: Purple is opposite from yellow on the color wheel. Violet hues naturally balance gold tones and are especially effective at fighting brassy shades, which is the most common offender. Here, seven shampoos that promise to keep your specific color just the way you like it.