The Rays' No. 13 prospect allowed four hits and struck out six over seven innings as the Double-A Montgomery Biscuits blanked the Jackson Generals, 2-0.
Colome (7-3) faced five batters over the minimum and threw 54 of 96 pitches for strikes en route to his fourth straight. He got some help from his defense as left fielder Brad Coon threw out Rich Poythress trying to score on Johermyn Chavez's two-out single in the seventh.
"He set the tone with the fastball," Biscuits pitching coach R.C. Lichtenstein said. "He got it down in the zone and let everything play off it real well. That was the biggest thing. He's got a big fastball and he was able to set the tone by throwing strike one and just working ahead of the count.
"Everything was working well. His changeup and his cutter played well, which are still pretty hard -- they're both about 87, 88, 89 [mph]. His curveball, he used to separate speeds, it's about 80 [mph]. He was able to keep everything around the plate and when he got to two strikes he had multiple options to put the hitters away."
The 23-year-old right-hander is winding down a strong month, going 4-1 with a 2.23 ERA. He's struck out 27 while allowing three runs on 15 hits over 26 1/3 innings in his last four starts. Lichtenstein credits Colome for changing his mind-set on the mound.
"He's bought into being simple and pitching," Lichtenstein said. "He's got a big arm. In the first half of the year when he struggled, he was trying to overthrow and rely on his fastball to beat everybody. He's started to realize the importance of executing with the fastball, of locating the fastball and getting it down in the zone. I think he's bought into the fact that he has to work down in the zone and he's got to be able to pitch with his stuff and not rear back and fire it by hitters."
Colome was 2-2 with a 4.21 ERA in six starts before the All-Star break. For the native of the Dominican Republic to take the next step, he has to continue to believe in what he's doing, Lichtenstein said.
"He's got to wrap his mind around the fact that he can pitch and not just be a thrower," said Lichtenstein, who's been with the Rays for eight seasons. "He's always had a marvelous arm and he's starting to get the fact to not just try and throw everything as hard as he can. He's now trying to make quality pitches consistently and embrace the fact that he just needs to be good consistently and not try and be better than that."
Shawn O'Malley scored the go-ahead run on reliever Jonathan Arias' balk with two outs in the eighth. Brett Nommensen added a solo homer in the ninth for the Biscuits.
Brandon Maurer, the Mariners' No. 14 prospect, struck out eight and allowed four hits over seven scoreless innings but did not figure in the decision for the Generals.