Clarification on #3
When is it put in? Is the clay formed like a roll of cookie dough with (diffrent color clay) inserts pressed into the sides then the dough sliced and pressed in to the mold? Or is it just a dye injected in the clay during the molding process? Some appear to be IN the clay some apear to be ON the clay.

Why is it used? To prevent conterfieting? Mark denomination? Just looks d*amn good? Some chips don't have them.