I am amending the particulars of this stone.
This thin stone is a Mohs -3 hardness. I was able to hone to shave-ready a handful of razors including a vintage Henckels 416 razor, an Inox Friodur, Swedish steel F&N-Kikuboshi, modern Hart Steel, antique Wade & Butcher (the Celebrated) and Towa tungsten steel. All with little effort.
A generous softer and tested tomonagura will be included:
#1571 Sumigashi thin razor stone
All of my stones are sold with a money-back guarantee minus the return shipping if within 30 days of the sale and returned in their original state. Please do not lacquer the stone if you have any intention of returning it.
I encourage sealing the sides of all sedimentary stones, especially if there a inclusions, cracks, or fissures and or if the stone is used in an active workshop where the stone is constantly wet. For casual use, sealing, especially all four sides, and preferably the back with one of either a marine type of spar varnish, a synthetic lacquer, urushi, or a cashew-derived lacquer is prudent.