The selloff in gold has run its course, and the precious metal is set on an upward trajectory, Dennis Gartman the closely followed commodities trader and founder of The Gartman Letter, told CNBC.

"I had been agnostic and modestly bearish of gold until about three and a half weeks ago," Gartman told "Squawk on the Street" on Tuesday. "Then I wrote what I call 'a watershed commentary' that gold was going to go several hundred dollars higher.