Abstract: A coloring system and a manufacturing process for coloring artificial covering stones are provided. A board layout represents a board of artificial covering stones. Several natural stone color patterns are provided, each being different from one another. The natural stone color patterns are associated with selected artificial stones of the board layout. Graphic parameters represent the natural stone color and are converted into coloring instructions. A conveyor conveys the board of artificial covering stones, and a positioning system determines respective positions of the artificial covering stones of the board, relative to a reference position. An in-line coloring device colors the artificial covering stones with the natural stone patterns, according to the coloring instructions and to the positions of the artificial stones. The selected artificial stones colored by the system are thus different from other stones of the board, and have a distinct, natural random-look.