Vintage Nakayama Maruka Yamazen Japanese Natural Sharpening Stone 807g (1lb. 12.5oz.) Size: 205mmX50-57mmX25-28mm
It has Maruka stamp on the side vividly, and Yamazen stamp on the other side. Yamazen is one of the dealership of Maruka (Hatanaka whetstone company). It looks very nice mixed color stone which are Asagi color (blue) and Kiita (brown color).
#6000 to #10000 or higher grit for finishing razor blade
It raises very good amount of black slurry, but it is kind of hard and condensed stone. It is very smooth stone, so it needs Tomo Nagura or a device that raises slurry like Diamond lapping stone.
(Scale; 1 to 10, 1-3 is very soft muddy rough grit whetstone 3-6 is soft medium grit whetstone, 6-8 is hard medium grit whetstone; 8-10 is fine grit whetstone)
Particle Size-------------- 8.8
(Scale; 1 to 10, 1-3 give deep scratch marks to the steel, 3-5 is delete the 1-3 scratches, 5-8 makes the steel cloudy, 8-10 makes the steel semi-mirror finish or mirror finish) It makes my blue II steel blade knife Jigane became from bright silver color finish, and Hagane became semi-mirror finish.
Nakayama whetstone is finest whetstone that is mined in Kyoto for almost 900 years ago. I think the mine had been closed more than 30 years ago. It had been very important as military affairs, because it is sharpener for weapons, so the mine had been protected by the Emperor of Japan or Shogun or Japanese Government for a long time. Only Honma family could have mined the mine for a long time. Nakayama Maruka is highly sought finishing whetstone even in Japan, because the mine was closed, and harder and harder to find. It is ideal razor hone or the cutlery that needs very fine finish.
Probably #6000 to #10000 or higher grit with the same as artificial whetstone.
Natural whetstone has wider capacity than artificial whetstone has, and actually, we do not know until sharpen blade on the hone for a while. Because artificial whetstone molecules do not break down to smaller sizes, but natural whetstone molecules are possible to unbond to smaller sizes, and those molecules are mixed with sharpened steel molecules, and make Jigane as suitable Jigane color, and Hagane as suitable Hagane color. It is natural mystics.