To craft a katana, iron sand is first drawn from the Earth and heated in a clay furnace. The sand is transformed into
tamahagne, a pure form of Japanese steel. Derived from tamahagane are two variations of steel, one of which is
shingane, used for the strong inner core of the blade. The resilience and strength of shingane are represented in the
dark green dial of the US Exclusive SBGA491.
