The 19-year-old has played a key role in Everton's bid to qualify for the Champions League, and Martinez believes that there are very few players of the same age who could be compared to him.
"His quality is not a surprise because I had the opportunity to follow his development when he was coming through at Barnsley and he has grown into a phenomenal footballer," the Spaniard told Sky Sports News.
"We need to allow him to develop, but he's a joy to have in the squad. He's so calm and composed on the ball and in the same way so aggressive in his defending. We are all excited about his development.
"He is going to have an England role. He is going to be an important player for English football, but we need to give him time and allow him to enjoy his football."
Stones moved to Everton from Barnsley in January 2013.