High school career
Stone graduated from Dominican High School in Whitefish Bay, Wisconsin. As a senior he averaged 24.4 points and 11.7 rebounds per game. He finished his career with 2,193 points. During his four years he helped lead Dominican to four-straight WIAA Division 4 state championships.
Stone was a five-star recruit. In March 2015 he committed to the University of Maryland, College Park to play college basketball. He signed on April 15. On December 30, 2015, Stone broke a Maryland freshman school record, scoring 39 points in a game against the Penn State Nittany Lions. On February 16, 2016, Stone was suspended by Coach Mark Turgeon for one game against Minnesota for hitting a Wisconsin player's head against the court and received a flagrant-1 foul.
At the end of his only season at Maryland, Stone would be one of 59 college/postgraduate underclassmen to enter the 2016 NBA Draft. Stone was projected to being either a late first round or early second round draught pick after starting out the season as a projected early lottery draught pick. Stone was drafted by the New Orleans Pelicans with the fortieth pick and traded to the Los Angeles Clippers.