This is a 175mm bunka with a 1.2519 core. 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 chocolate and blonde box elder burl.
Disclaimer: This wrought iron is extremely old and has large silica deposits in the iron which create voids during grinding. This knife has a few spots on the bevel of the stamp side. I do not believe it is or will become an issue. This is merely a characteristic of such old wrought iron.
Out of the handle: 4.06mm
Above Makers Mark: 2.86mm
2cm from tip: 1.54