Pearl, much like candy apple, is a process not a color. You can't print them because they don't exist. They're the result of a base coat and layers of clear. In the case of pearl [in the past at least] the base coat was made from ground up fish scales. If memory serves. Probably something synthetic now. Candy colors have a metallic base coat. In both cases the particles of the base coats sort of stand on edge rather than lay flat. The sufficient layers of clear coat, tinted if need be, is added to give it depth and the right color. I'm not at all certain what the process is for modern production autos but if you put one next to a real pearl paint job there's a distinct difference.