Kolesar scored on a rebound at 11:19 to make it 3-1.
The Golden Knights then scored two straight power-play goals, Karlsson at 14:56 to make it 4-1, and Stone at 18:08 for the 5-1 final.
Golden Knights defenseman Shea Theodore had an assist on the fifth goal, his 100th with Vegas.
"We didn't play well the first two periods, but we hung in there," Berube said. "We get outshot 15-3 in the third period, it's just not good enough. I've got to coach better, they've got to play better. I guess I didn't prepare them good enough."
It was Stone's third game this season with at least three points.
"We were doing some good things," Stone said. "That was a big win."
NOTES:The Golden Knights have scored 19 goals in four games against the Blues this season, including five in three straight. … Dunn scored for the second consecutive game; he didn't have a goal in his previous 20. … Blues forward Robert Thomas was minus-1 in 13:26 in his first game since Feb. 6 because of a broken thumb. … Vegas forward Max Pacioretty missed a second consecutive game with a lower-body injury. ... Golden Knights center Cody Glass was a healthy scratch. Forward Patrick Brown took his place in the lineup and had one shot on goal, two hits, and one blocked shot in 11:24.