"Purple shampoo is amazing on pale blonde hair as it neutralises unwanted yellow hues leaving the blonde bright and cool-toned," explains Christel Barron-Hough, Founder & Creative Director Stil Salon.

For the event, Hadid stepped out in a full glam look that required a hair change—she wore a glittering yellow and silver ... Hadid swapped her signature blonde locks for a silver bob with ...