This is a 245mm gyuto with a 1.2519 core and wrought iron cladding. The 1.2519 core steel is German Tungsten tool steel which is quite similar to blue2 (aogami2). The cladding is ancient wrought iron which has been etched reveal the brilliant detail of the iron. There is a piece of pure nickel separating the cladding and the core steel which minimizes carbon migration. The handle is stabilized and dyed purple box elder. The ferrule is ancient bog oak
Out of the handle: 4.35mm
Above Makers Mark: 2.69mm
2cm from tip: 1.29mm
Disclaimer: This wrought iron is extremely old and has large silica deposits in the iron which are naturally occurring and sometimes this results in small voids in the iron. This is the nature of old wrought iron and part of what gives it its beauty.