Gray's superb solo effort sealed a deserved 2-1 Midlands derby win for Blues at St Andrews on Saturday afternoon.
"I tend to always start him at home because in front of our fans he always comes up with something special," Rowett said after the match.
"To run the length of the pitch and show the persistence after loosing the ball and regaining possession you have to give him great credit.
"But he always does the right thing in front of goal when he is one on one with the goalkeeper.
"It shows testament to his ability and deep down he has a little more than other players. It is in moments like that you see real quality.
"We are trying to do the right things for Demarai. Not just for the club. He is an 18-year-old player. We cannot play him in every game. We cannot expect everything off him all the time.
"The whole speculation will undoubtedly affect him. We have to be patient and give him confidence. He repaid that faith with a fantastic winning goal against local rivals.
"In many ways it was as complete a performance since I've been here.
"I was impressed with different facets of the game and the way we always looked dangerous.
"I don't think many people will argue that we didn't deserve the win."