Kuro Nagura is a small auxiliary stone used to prepare or improve the surface of a finishing stone.
The term Nagura refers to a stone that is rubbed on the main stone to create a slurry of sharpening ( tonoko ), essential for obtaining a fine polish, reducing friction and improving the quality of the cutting edge.

This black nagura stone produces a dense, homogeneous slurry, ideal for accelerating the final polishing of blades, particularly on natural stones or high-grit synthetic stones. A protective coating ( kashū lacquer, a synthetic lacquer) is applied to the sides to prevent cracking.

Compact, durable and perfectly suited to demanding sharpeners, it is an indispensable complement to achieve a mirror finish and a razor edge.