Natural polishing stone used for Omote-zuri for Uchigumori-do and Suita-do.
Omote-zuri is a work to smooth the surface of the polishing stone.
Polishers always use natural stone for this work, because if any particle of artificial stone remains on the Uchigumori or Suita, it will scratch the blade.
Tsushima is the finest stone among our 3 Omote-zuri stone and it is almost the same grit as Chu-nagura.
Tsushima-do For Omote-zuri is very soft stone and very easy to be cracked.
It might be better to protect the side of stone with water proof tape or something before using.
Dimensions : about 4 x 4 x 4cm.
