Vintage Nakayama Maruka Iromono Nashiji Japanese Natural Sharpening Stone
914g (2lb. 0.2oz.) Size: 137mmx83mmx30-32mm
It has Maruka stamp on one of the side face.
The stone is very nice light color Kiita(egg york color), and pinkish color (iromono) and tiny Nashiji dots are on the sharpening surface.
It is thick and very nice shape razor size stone.
All the lines on the sharpening surface are minor and very tight, so they look they do not bother sharpening.
#6000 to #10000 or higher grit for finishing razor blade or high carbon steel blade.
Hardness--------- 8.8
It raises good amount of black slurry, but it is kind of hard and condensed stone.
It is very smooth stone, so it does not need 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-------------- 9.0
(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 to semi-mirror finish, and Hagane became mirror finish.
Nakayama whetstone is finest grit whetstone that had been mined in Kyoto for almost 900 years. 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 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.