Rita Hazan is a celebrity colorist, working with Jessica Simpson, Beyonce, Jennifer Lopez, Mariah Carey, Katy Perry, Madonna. She attended beauty school at 17, opened a salon on 5th avenue & has her own product line. She worked with Oribe before going off on her own. 

https://thestylethatbindsus.com/the-colorist-behind-mariah-carey-j-lo-jessica-simpson-podcast-interview-with-celebrity-colorist-rita-hazan/