By looking at those pictures I would say 4 pieces of leather. Single back piece, folded at the top and run down, maybe all the way to give double back layer. keeper strap sewn into fold of Back. Then front piece, pre molded and sewn into place. Stone keeper added whensewing gets to that point. All leather looks fairly thin to me and the tops of the front piece and stone holder look to be folded over for smooth edge. File edge looks like it has some sort of fold too, looking at the bottom corner.
JMHO