CLEVELAND – Barber Nick Castemanos has grown tired of getting asked over and over again about the hairline of his most famous client, LeBron James.

"There is no dye. No additives. No preservatives," Castemanos told Yahoo Sports in a phone interview Thursday. "Everyone thinks he's dying his hair using [temporary hair colorings] Bigen or Black Ice. It's all his hair. They still don't believe me. I get Bigen comments all the time.

"I've become numb to it. It used to bother me. It's not easy to hear that."

Castemanos has one of the cooler jobs as James' new personal barber.

View photos Nick Castemanos has cut LeBron James' hair all over the world. (Derick G.) More

Castemanos first began cutting the hair of NBA players in the early 2000s in Miami. Former Miami Heat swingman Dorell Wright initially introduced Castemanos to Heat guard Dwyane Wade. Through Wade, Castemanos said he often landed private jobs cutting players from teams visiting Miami. Los Angeles Lakers guard Kobe Bryant and film producer Spike Lee are some of his past customers. While Castemanos' celebrity list grew, so did his reputation as an elite barber.

James' four-year tenure with the Heat began when he signed as a free agent in 2010 after departing from the Cavaliers amidst chaos. In October of 2010, Wade set up James with Castemanos for a haircut. Castemanos quickly hit it off with James and has been cutting his hair all over the United States ever since.

"I was a little star struck at first," Castemanos said. "But LeBron was very cool and welcoming. And this was after going through a lot of scrutiny for coming to Miami."

Of all his customers, Castemanos says James is the most challenging and meticulous with his hair and beard. A typical haircut for the NBA's most heralded player takes nearly an hour.

"LeBron is very tedious about how his hair is cut," said Castemanos, who has been a professional barber for 11 years. "The beard is the No. 1 thing. He leaves the top up to me. I leave him less bald. He's my guy.

"He's my hardest haircut. He has good hair. You have to cut it right. He just has a few fat patches around the chin that you have to take your time with. You have to have patience. It usually takes about 50 minutes."

Since 2014, Castemanos has gone to Portland, Los Angeles, New York City, San Francisco and Cleveland to cut James' hair. Castemanos was summoned to a Sprite commercial shoot in Akron, Ohio, last August when James made him a life-altering offer, asking him to move to Cleveland to become his private barber – while also allowing him to take clients on the side when he was available.

"LeBron said, 'Hey Nick, I really think you should come to Cleveland to work for me,' " Castemanos said. "I didn't give him an immediate yes or no. But his mom said, 'You better take it.' "

View photos Castemanos has been cutting James' hair since James played in Miami. (Special to Yahoo Sports) More

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