You're looking at a stamp made from solid stainless steel in Japan.
Surface is shaped so precisely that you can have the sharpest result on leather. Especially great for sheridan style.
You can grind the stamp shape into your own design with no worry about getting rusted becauase it is made from solid stainless steel.
Stamp type: Stainless Steel Stamp
HOW TO USE
Leather must be moistened by rubbing a damp sponge on it. Place leather on top of a firm surface like marble or rubber board. Use a wood or raw hide mallet head to strike the top of the stamp to obtain its impression in the leather. Control over degree and force of striking depend on the case.