The Kyotoyama HSS #250 is a coarse Japanese sharpening stone specially designed for very hard steels such as HSS (High Speed Steel) and Aogami Super (Blue Super Steel).

Thanks to its high abrasive capacity, it quickly restores dull edges, reshapes a bevel, or corrects a blade before finer sharpening. Its ceramic structure ensures effective cutting even on modern, hard-to-work steels.

Before use, the stone should be immersed in water for approximately 5 to 10 minutes to ensure good absorption.