Carolyn Bessette-Kennedy’s hair colorist Brad Johns on what Ryan Murphy’s ‘American Love Story’ got wrong

She’ll always be a style icon.

When Ryan Murphy posted the first look at his forthcoming FX series, “American Love Story” — focused on the late Carolyn Bessette-Kennedy and John F. Kennedy Jr. — fans were immediately up in arms.

The test shots showed Sarah Pidgeon in character as the former Calvin Klein publicist, complete with a sad-looking camel overcoat, too-small Hermès Birkin bag and white-blond hair that was “burnt,” according to CBK’s real-life hair colorist, Brad Johns.

Page Six Style spoke with the beauty guru, who was close friends with Bessette-Kennedy and became world-renowned for his “chunking” style that he used to take her from light brown to iconic, buttery blond.

“I love Ryan Murphy. I mean, I live for him. But there must be some kind of glitch with the costume people or the hair people, because it’s not right — it’s all white and burnt,” he tells us.

“Her hair was not white and it wasn’t burnt, and she hated the idea of having ashy hair — which I was totally against, too, and I never did it. But when I saw [the first look], I went, ‘Oh my God, what am I gonna do?’” says Johns, whose memoir, “Dye,” chronicles his career.

“Carolyn’s hair was darker at the bottom, the mid was medium blond and the front was all brilliant gold pieces. Gold makes women look beautiful. Ash makes you look dead, unless you’re wearing a ton of makeup, and who wears a ton of makeup? It’s just wrong. Everything.”

The pair first met when Johns was serving as color director for Oribe at Elizabeth Arden, and he gets emotional recalling their friendship.

“I was the top colorist in the world at that time,” he recalls. “And she sat down, and she said, ‘I work for Calvin, and I don’t like my hair, and I need you to make me blond.’ I said, ‘I will make you blond, but it doesn’t take one day.’ She said, ‘Just do it. Just do it. I trust you.’”

Johns remembers how Bessette-Kennedy could command a room (or crowded salon, as it were).

“She would walk in with no makeup on, and I always had eight chairs going at once. And people would turn around and go, ‘Who is that? She looks like an angel.’ Oh, she was angelic. And so funny,” he says, calling her a “fawn.”

While Johns has since pivoted to glassblowing, his first love was always hair.

“You know, I got this gift from God — I know how women’s hair color should look. I don’t know where it comes from,” he tells us.

“I used to do little troll dolls when I was little — because they never had the right color — with food coloring, and it’s just a gift.”

Speaking with Puck’s Lauren Sherman, Murphy responded to the backlash over the first look shots.

“That is not the wig we’re using, that is not the purse we’re using. Those are just things we had to show the studio,” he assured fans.

“It was a work in progress, but I released it, because sometimes you put things out and the paparazzi backs off, so your actors don’t feel attacked.”

Murphy even promised to invite a group of 20 CBK-dedicated fashion bloggers to come see all the clothes they’re working with in the fall, and said he has an advisory committee working with his team. For research purposes, he’s even collected a range of vintage designer items Bessette-Kennedy is known to have owned and worn, including a pair of Prada boots, a Miu Miu turtleneck and several ’90s Calvin Klein styles.

“I had no idea that people cared as much as they do, but I guess that’s a good thing,” he said.