It kind of depends a bit on the stabilization colour. Your pictures show colour relief where it is carved, that will not necessarily be how the colour changes. It may wind up being a difference in texture more than a difference in colour. So in example drawing one, everything will be the same colour, the cross would be polished and the rest of the scale would be textured. It is much more subtle than in your example and I have no idea how that would be drawn on paper to show it. A small inlay as a relief within a textured scale would have it stand out.