This blade features an oxidised colour finish (酸化色仕上 / Sanka-shoku Shiage), a modern aesthetic treatment that gives the steel a deeper, more nuanced tone than the standard silver finish. Depending on the blade and lighting, this patina oxidation can result in subtle hues—such as grey, violet, bronze, or blue—emerging across the surface.

While the exact method varies by maker, this finish typically involves controlled oxidation or surface treatment, applied to enhance visual depth and showcase the blade’s refined form. Unlike traditional mirror or kasumi finishes, Sanka-shoku Shiage brings a modern, moody elegance to the blade without altering its performance or geometry.

This type of finish is often used by contemporary blacksmiths working in monosteel or Honyaki, and reflects a balance between function, steel artistry, and individual craftsmanship.