Natural stones, or JNATS or Tennen Toishi are natural sharpening stones quarried in various mountains in Japan. Made by natural thanks to Japan’s rich sedimentary and geological history. Japan is one of the only countries where such a diverse amount of silica and aluminium oxide rich stone can be found. These two elements give the stones the ability to cut steel in an effective way.  The presence of natural sharpening stones is what gave Japan its history of swords and high quality tools. They have incredible historic and cultural value and the world of naturals is as complicated as it is fascinating.