The Shun Blue Steel line is made of Japanese san mai construction; blue #2 carbon steel is sandwiched between two layers of stainless steel for the ultra-sharp benefits of carbon steel without the additional maintenance. Blue #2 steel is hard and takes a great edge and you will see patina form right on the edge where the blue steel is exposed after use. You still need to keep these knives dry after use.
This is a really good knife. The weight is off a bit and itís very lite for a boning knife. The blade retention is great though and it continues to surprise me with my everyday use of it. Caution- its a two sided blade which Iím not a fan of but never the less it gets the job done.í