Tsushima Black Kuro Nagura - Japanese Natural Stones

These are extremely high quality and consistent nagura, from a supplier in Japan specializing in sword polishing (the highest grade) stones.

The Tsushima Black Nagura is often used as an intermediate hone in straight razor sharpening, positioned after the Botan and before the Koma. Known for its hardness, the stone generates a slurry that begins at a medium-fine grit but gradually breaks down into a finer consistency during use. It is also valued as a starting point for razor touch-ups, offering a slower but highly efficient cutting action. 

These are very clean and consistent Tsushima Kuro Nagura. These are mined underwater as opposed to in traditional mountain mining. They offer extremely consistent particle uniformity making them excellent for honing razors as well as other purposes. I find them to be one of the only natural stones that can be spoken of in general terms as they're very consistent from sample to sample. Most of them lie in the Medium Fine category and they do a great job of removing medium grit scratches. 

All sides except for one have been coated in cashew lacquer.

Approximate Dimensions/Weight:
40 mm long × 40 mm wide × 40 mm tall / 250 grams