Nakayama Hon Suita ..
I was told it is one of a kind.
It is the hardest stone i've encountered, requiring a lot of work with a diamond plate to generate a slurry and it cuts so fast that it is unbelievable. It has also reshaped some of my naguras.
Very fine too. It can deliver the highest levels of smooth & sharp. It is pretty too :)
Attachment 322343
Attachment 322344
Attachment 322346
Attachment 322347