In 2004 a salesman called on Rita Hazan's Manhattan salon, trying to sell her a product that, he said, would give her clients honey highlights just like Jennifer Lopez's. Before he finished his pitch, recalls Hazan, "I laughed and said, 'I created that color. I do her hair.' The guy got a little embarrassed. He said, 'Oh.'"

Like the befuddled color salesman, you may not recognize Hazan, but you know her work. Creating copy-worthy looks for Britney Spears, Shakira, Jessica Simpson and Brooke Shields has made Hazan, 32, among the most sought after—and expensive—colorists in the country. At her new 6000-sq.-ft. Fifth Avenue salon, getting a color change plus highlights costs $600. (For clients on location, she'll hop a jet for an additional $5,000, because "roots happen no matter where you are.")

Pricey, yes, but Hazan sees changing your hair color as more than just that: She sees it as a way to change your life, whether that means raising your star profile or cutting free from a failed marriage. Remember Britney's sunny blonde bob, which she premiered on David Letterman's show the day before she filed for divorce? That was Hazan too. "Her blonder look said, 'I'm Britney. I'm back,'" says the colorist. Likewise for Simpson, who went superblonde when she separated from Nick Lachey. "A lot of women do this. They want to feel sexy and in control of their own lives." A year later Simpson, sporting a toned-down blonde, says of the woman who took her hair through its transition, "She's not only a true talent, but also a friend."

More recently for Lopez, Hazan whipped up a rich chocolate brown, which the star wears opposite husband Marc Anthony in their forthcoming film El Cantante. "The color says she is glamorous and exotic, sophisticated and mature," says Hazan. On the horizon: something more dramatic for My Name is Earl star Jaime Pressly after she gives birth in the spring. Even if you find a color that works for you, says Hazan, "everybody needs to change. To stay stagnant is the worst thing."