My birthday is coming up and a good friend sent me this wonderful stone as a gift. He said it's an "Okudo tenjou suita". The bottom of the stone was uneven so he made it flat with epoxy. I glued it to a piece of Teak which I varnished beforehand and placed a small rubber foot on each corner so it doesn't move around. The glue was dry this morning so I gave it a test run and it's a very fine stone, it must be in the neighbourhood of at least 10.000 grit. And I love the finish, there's a very clear distinction between the soft and hard steel and the hard steel becomes very bright with this stone.