Ruud won the Nordea Open last weekend and added a fourth ATP Tour title of his career with a 6-3 6-2 defeat of Frenchman Gaston.
The Norwegian took his tally of tournament victories on clay this year to three, having also won the Geneva Open in May, and the 22-year-old will rise to ninth spot in the ATP Race To Turin on Monday.
Ruud saved nine of the 10 break points earned by first-time ATP Tour finalist Gaston, who only won 51 per cent of points behind his first serve.
Gaston, who had never been beyond the second round at an ATP Tour event before this week, was broken twice in each set as the 20-year-old was unable to halt Ruud's brilliant run on clay.
Left-hander Gaston broke straight back after Ruud went 3-1 up in the opening set but failed to back that up with a hold.
Ruud had as many as 16 break-point opportunities but got the job done in an hour and 34 minutes.