The scales look like dyed horn to me too. I had some almost identical to them and when I unpinned them the inside was clearly horn and the dye was only on the show side. From my limited handling of R eal tortoise scales they will not have defined lines but will be more of a natural blending into the rest of the piece. The markings have been part of the shell and not just on top. Of course I've been wrong before and I am FAR from a "tortoise shell expert".