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Japanese Natural Stones (JNATS) Glossary & Kanji

Ai-ishi Naori – 合石成り

Meeting Stone Strata – the literal translation is Synthesis Becomes Stone. One of the 3 strata that Japanese natural whetstones originate from. Stones from this strata are known to be coarser and softer than those from the Honkuchi or Chuishi Naori.  Hideriyama stones come from this strata. 

Aisa – 合さ or 合砥

Meeting.  This is a layer of stone in the Honkuchi Naori, it is located below Tomae and above Namito. Often very hard. Karasu stones come from this layer, though not all Aisa are Karasu. When it is not Karasu it more commonly has the Tamamoku attribute, but that is not individually unique to the Aisa layer. Tends to have a lot of abrasive force but also a higher probability for impurities.

Aiiwatani – 相岩谷

A Higashi Mono (Eastern Mine) north of Kyoto located by Takashima and Wakasa. This area is known for its high density stones. Aiiwatani tends to produce harder stones.

Aizu – 会津

A Northern Japan mine producing medium-coarse whetstone. Useful for knive sharpening with a toothy edge, late middle stage polishing and for setting bevels on straight razors. This stone is a form of Dacite with Feldspar inclusions which show up as white dots within its surface. It was quarried in Fukushima. While most mines stopped production in the 1980s, due to an incident within the mines causing wide-spread lung disease all stock is from 1950s or before.

Akapin – 赤ピン or 赤不动

Shallow layers, softer stones. Used to be very common, it is less so now. This can also indicate the coloring of the stone itself, usually a deep red to pink color. These stones can range in coarseness and fineness, it is hard to draw a specific broad performance level for them. Soft and fine ones are capable of razor work and are very nice to work on.

Amakusa – 天草

A South West Japan mine producing whetstones quarried in Amakusa, Kyushu. There are two types: red and white. The white examples are usually finer and slower (1200), the red variety are very coarse (800) and faster. The grain structure is often uneven and difficult to work with when honing razors. This mine is still active.

Ani Ishi – 阿仁石

A Northern mine producing rough quartz rock and crushed stone.

Aoto – 青砥

Blue Whetstone.  Ao = blue, To = whetstone. This is a lower to mid-grit type of whetstone. Most known to have been mined in the Tanba region. Aoto can be soft, or somewhat harder. Many of them are soft and coarse, but the harder examples are known to be much finer. In the past, an Aoto’s qualities were assumed to be one way or another based on exactly where it was quarried. Tanba is a word used to generalize the area where Aoto was mined, but there are precise quarry locations that are now almost forgotten, such as Sakei, Kouzaki, etc.

Ara To – 荒砥

Rough Grit Stone. One of the Ryūdo Kubun 粒度区分 or Granularity Classification.

Arado / Arato – 粗砥

Sometimes also referred to as Arame. It means coarse grain.

Aratoishi – 荒砥石

Rough Grindstone. Arato (粗砥) stones are used at the beginning of the heavy work when shaping a blade.  These coarse grained or rough grained stones are used for cutting steel and establishing geometry. A sword polisher will have Arato stones of several types of varying grit.

Asagi – 浅葱 orアサギ or 浅葱色 or 浅黄

This color indicates a very light/thin colored indigo, almost neutral grey. Often mistranslated as shallow yellow or light yellow. This is a color that is attributed to grey whetstones. It should now be accepted that it could range from blue to even dark yellow as that is how the term will be commonly used.

Asano / Inspected by Asano – 検浅野

Red stamp originally used by Nagayuki Asano to grade nagura based on strata and progression performance. The stamp was passed onto Sakamoto Misao for the same purpose and continues to be used on Mikawa Asano Nagura to this day which have been properly inspected.

Atagoyama – 愛宕山

A mine at Atago Mountain, it’s known to produce large clean whetstones from the Chu-ishi naori. These stones often have this stamp; 愛宕砿山合砥. – Atago-Kouzan-Awasedo. 

Atarazuno Hari

Reflective needle, point or dot pattern. This ‘safe’ pattern is said to be a very uncommon characteristic. See Harike for the toxic variety.

Atsu – アツ  

Thick. A medium-coarse Mikawa Nagura, usually used for sharpening scissors and similar cutting tools. Can also be used at the very start of a razor progression.

Awasedo –  合砥

Finishing stone. Finer than Shiage Toishi, another type of finishing stone. This is the more common term used to refer to all finishing stones.

Ban – バン  

No distinct translation. The most course Mikawa Nagura, one of the usable layers of stone that are quarried. Generally used for sharpening edged tools.

Bestu Dai Jou – 別大上  

Superior Selected Grade. One of the Asano quality stamps used on Mikawa Nagura; it indicates that the stone is white with a uniform square shape. Can also be used to indicate Betsu Ōgami, for a large Koppa size Nagura.

Betsu Jou – 別上

Superior grade. One of the Asano quality stamps used on Mikawa Nagura; it indicates that the stone is white with an odd shape.

Binsui – 備水

This is the first stone that follows Arato or Kongo-Do in a sword polishing progression. These are Nakato, or middle-ground whetstones that are quarried at Amakusa on Kyushu. The Binsui-Do is used to remove the scratches from Kongo-Do. An approximate grit range for these stones might be rated as being somewhere between 800x and 2k.  This mine is still active.

Botan – ボタン

Peony. A medium-coarse Mikawa Nagura and the most course Nagura in the typical 4-stone Nagura set used by people honing straight razors.   

Bouoku -茅屋

Thatched cottage; hovel; my humble cottage. The word Bouoku is sometimes used when referring to good quality but unstamped Tennen Toishi.   

Ceiling Nest Plate – 天井巣板 or 天井巢板

This term refers to stones that come from the seams in the Tenjyou Suita strata.   

Chu Nagura – 中名倉

This is a mid-range stone. In a sword polishing progression, it is the last stone before Koma Nagura Do. High quality Chu Nagura can be used successfully when honing razors or sharpening cutlery. Chu is from its own mine on Kada mountain beside the mountain Mikawa comes from, but often Mikawa Nagura are sold under the Chu name when the layer of Mikawa is unknown. They are technically different things, but the term is so often used this way it needs to be considered. Anything Mikawa Chu isn’t real Chu, but may perform similarly.

Chū To – 中砥

Medium Grit Stone. One of the Ryūdo Kubun 粒度区分 or Granularity Classification.

Chu-ishi Naori – 中石 成り

Stones from this Naori are softer and less fine than those from Honkuchi. They are generally very consistent and of good size. Whetstones quarried at Atagoyama are from this Naori. These stones are described as having the ‘ball’ form, which means they are all one layer. 

Diamond Nagura

Also referred to as a DN. A diamond plate used to generate slurry. Atoma Diamond Plates are a common high quality brand.

Enshou – 煙硝  

Firecrackers. This characteristic is usually the result of sulfur in the stone; usually seen as blue/black spots or lines. This can also be referred to as Ao Renge or Kuro Renge (黒蓮華). It’s been said that the sulfur in the stone can cause a discoloration in certain types of steel, but not all Enshou has this issue.

Gokudo – ごくどう

Rogue or Wicked. It is a nickname for the layers of unusable stone in Higasshimono mines which surround the usable layers. It is a very hard layer and can be very frustrating for miners to work through.

Gokujyohin – 極上品

Best quality. A stamp seen on some Tennen Toishi.

Gotogi – 合砥

Layered, or to be together. Many Japanese Natural Whetstones, such as those from Tomae strata, were formed with layers that can be seen on the sides of the stone. 

Goma – 胡麻

Sesame Seeds. These are small black dots that look like sesame seeds. Many people believe this pattern indicates that the stone will have good speed. Goma can be ‘safe’ or ‘toxic’; if they are too hard, they can scratch a fine edge. The vast majority will cause no issues.


This is a deep seam in the Tomae strata; it has been said to be located next to the Aisa strata. Some experts disagree and say it is a seam in Aisa that it just below or next to the Tomae strata. Toishi from this seam are usually hard or very hard, but in some cases can be softer but almost never very soft.  

Ha – 刃           

This is the hardened steel section of a blade that forms the cutting edge.

Habiki -刃引き  

Pulled edge. A sword with a dulled or blunted edge. 

Habutae – 羽二重 

Fine Silk. A color characteristic attributed to certain very white Suita, sometimes also called ‘rice cake’.

Hachi-mai-sō -八枚層

May also be referred to as Hachimai (八枚). 8 layers. This refers to the 3rd deepest strata in the Hon Kuchi Naori. It is directly below Tenjyou Strata, and just above Senmai Strata. It is known for being harder and finer. Was commonly sought after for razor/barber hones.

Hagane – 鋼   

Steel. Also called kotetsu. Literally, this is the harder ‘edge’ or core steel that is supported by an outer layer of soft Jigane.

Hamon – 刃文

Blade Pattern.  On a sword, this is the outline of the hardened zone known as the Yakiba, which terminates at the cutting edge or Ha.  

Hakka – 八箇

This was a whetstone mine that produced many good stones. Generally speaking, they are usually softer and coarser.

Hanko -判子

Seal. A stamp used in lieu of a written signature.


This term is used to describe a toxic needle pattern. This is a toxic inclusion and it can scratch the steel and possibly damage an edge. It is usually reflective unlike Atarazuno Hari.

Hatanaka – 畑中

This is a family name that belongs to the final owners of the Nakayama mine. They are still in business selling Tennen Toishi.

Hazuya – 刃艶 

This is a very thin slice of Uchigumori stone that is fixed to paper. Often called finger stones.

Heikin kōdo -平均硬度

The average hardness.

Hideriyama – 日照山

A whetstone mine known for producing good quality stones that are generally expected to be softer and more coarse that hones from the eastern mines.

Higashi Mono

Eastern mines of Kyoto, e.g. – Aiiwatani, Narutaki Mukoda, Nakayama, Okudo, Ozuku and Shobudani.

Higonokami – 肥後守

A traditional woodworkers knife with a laminated steel blade and brass scales.

Hikikoro – 抽 轆

A slang word referring to Koma shaved by hatchet.  The weight is about 200g. 

According to Mr. Kosuke Iwasaki, Koma was not cut with a hand saw, it was shaved with a hatchet at the mine area; the other Nagura were cut with a saw after it was taken to the village near the mine. Also – see – Kiridashi

Hinoki -檜

This is one type of Japanese cypress used for making a Toishi Dai.

Hin Shitsu Yuu Ryou – 品質 優良

Excellent Quality Product. This stamp is sometimes seen on finishing stones.  

Hoboyo – ほうぼうよう

Sometimes called “硯”, Suzuri, or Inkstone these are Mikawa nagura that are unmarked from the layer and used to flatten out the high spots or sides of your whetstone. Often a diamond plate in modern use takes this function, but these are sold specifically for this purpose. They tend to be smaller than regular Nagura, being thin and larger than most coins but smaller than your palm. These stones will still carry the Asano and Mikawa stamps, but will lack a strata stamp. They will be marked “鋒鋩用” instead of the normal Betsu or Tokkyuu designations.

Hodoyoi Kata – 程よい硬

Reasonable hardness.

Hon Suita – 本巣板 or 本巢板

A total of 6 seems to this Suita layer. They are highly sought after and come a variety of colors and attributes. These are usually hard Suita.

Hon-kuchi Naori or Honguchi Naori – 本口成り

Becomes the Mouth. This indicated the main opening strata. This is one of the three stone formations that Japanese whetstones originate from. The stratum in this formation is known for producing the hardest and finest stone. Many mines are connected by this seam, which runs from Maruoyama/Ouchi/Yaginoshima east across the Tamotsu-gawa (Katsura) River, to the Hakka mine, South-East to Okunomon, Ohira, Atagoyama, Ozuku, Okudo, Nakayama, then turns north to Narutaki and Aiiwatani. Certain levels of these seam can often matchup between the mines, creating similar stones and colors such as for Aiiwatani and Nakayama.

Honyama – 本山

True Mountain. These Kanji are also used for ‘Honzan’. Originally, Honzan and Honyama were terms used specifically and only when referring to a natural whetstone from Nakayama or Shobudani. In more modern times, they are used generically to mean any awasedo from the Kyoto region.

Hosome -細目

Break Down. Used when describing what happens when working slurry on a Toishi, as it refines. It may also refer to the quality of the stone, indicating fine texture.

Ikarashi – 五十嵐

Also referred to as Igarashi, Igarashi To, or Kasabori. These medium coarse whetstones are Nakatoishi, or Chu-Shiage stones. Reportedly, the blue examples are finer than the white ones. These stones are from Niigata, with a few different mine veins around the area. The original mine vein was in Kasabori, Niigata but has since been exhausted. Kasabori Ikarashi is very hard and very close to Aizu in performance, whereas newer Ikarashi which drops the Kasabori name tends to be a little softer and a little course making it more clearly slot between Binsui and Aizu in performance. Non-Kasabori Ikarashi will be much more pure emerald in color when wet, whereas Kasabori Ikarashi will have white dots like Aizu and retain the very dark Emerald color compared to the lighter emerald color of Aizu.

Iki Murasaki – いきむらさき

Purple-ish. It is an uncommon color of Maruoyama stones, commanding a higher price.

Imo-ishi – 芋石

Potato Stone. This term refers to Japanese natural whetstones that are homogenous, without any layering. These Toishi can be used on any side. Many Aoto are potato stones.

Iromono – 色物

Colorful Laundry. This characteristic shows as abstract splashes of color; red, pink, violet and possibly other colors mixed in as well. This is seen most often in softer Kiita stones. 

Ji – 地 

This refers to the section of the blade between the Hamon and the Shinogi.   

Jigane – 地鉄             

This is the softer outer layer of steel that supports the harder Hagane.     

Jinzou Toishi – 人造砥石

Synthetic whetstone.

Jizuya – 地艶 

This is a type of final polishing stone; usually quarried at Narutaki. It is used to polish the Ji. 


Shortened term used to refer to Japanese Natural Stone / Japanese Natural Stones.

Jyunhonyama Awasedo –  純本山合砥

Real authentic finishing stone. This stamp is found on some Awasedo.

Junzo Kawashiro Nagura – 純三河白名倉

Another name variation for Mikawa Shiro Nagura.

Kaeri  – カエリ

Burr. A small curl of steel coming off the apex of the cutting edge.  

Kaiji Oshi – 鍛冶押

Rough Polishing. This is the final stage of the smiths work. At this juncture, the blades’ lines and basic geometry are established. This allows the smith to inspect the steel to ensure the absence of cracks or defective welds.  Also called Kajitogi. The smith will also add his signature, drill the hole for the Mekugi, and add any decorative work if needed. After this, the blade will go to the polisher.  

Kaisei – 開成

This is the 3rd stone in a modern sword polishing progression. Known as Kaisei-Do, this stone removes the scratches left by Binsui-do and it precedes the finer Chu-Nagura-Do.  An approximate grit rating would be 3k-5k. 

Kakishibu – 柿渋

Named after a traditional dying method using discoloration caused by the oxidation of fermented juice. It is a visual quality to certain stones characteristically identified as a whiteish background color with circular or round blotches throughout in a light to dark brown variety. This pattern can form the look of droplets or standing water on the surface of the white background. Most common in Suita stones.

Kamaboko – 蒲鉾

Loaf Shape. Sometimes used to describe the shape of the stones used by Togishi for polishing Nihonto.

Kamisori – 剃刀   

Japanese Razor. Usually indicates a Japanese-style straight razor that does not fold into scales. This style of razor has an assymetic grind pattern to it which requires sharpening in a specific manner.

Kamisori-to – 剃刀砥

Razor Strop.

Kamisorido – 剃 刀 砥

Razor Sword Whetstone. This quality stamp can be found on vintage stones that are hard/fine and selected for honing razors, or stones that are cut smaller for use as razor hones.

Kan – 環巻

Ring Winding. A pattern in the stone that resembles the age rings in a tree. Sometimes, very pronounced Kan rings can be invasive and scratchy. The darker rings can be of a different density that imparts a change in the feedback on the stone. However, most of the time, Kan is not invasive and safe to hone on.

Kanato-ishi – 金砥石

A flat metal plate for sharpening woodworking tools. A small amount of abrasive emery powder is sprinkled on the plate.

Kata – 硬

Hard. One of the Kōnan-do Kubun (硬軟度区分) or hardness classifications.

Kata-ishi – 硬石

Hard stone.

Katai ishi – 硬い石

Harder/solid stone.


A kamisori style razor with an asymmetrical grind which folds into straight razor scales.

Katakuchi – 硬口

Hardness ports are tightened. This term is used when describing the hardness of a toishi that is very hard.

Kane – かね

Metal-like. This is a layer of stone which sounds like metal when hit. It is between the usable layers on Nishimono mountains. It does not produce usable stone.


This is a hairline inclusion that is toxic. It can be felt under the blade when honing. It contains very hard particles that can damage the edge. They are often reflective.

Karasu – カラス or 烏

Crow. This is an abstract pattern that resembles a blurred flock of crows flying against the sky. Dark Karasu spots can possibly be scratchy; meaning, the darker spots in some Karasu patterned stones may scratch certain steels. Additionally, very lightly patterned Karasu pattern are highly sought after. This pattern is associated with stones from deeper layers, such as Aisa. Karasu stones have a reputation for being hard, though exceptions exist.

Kawato – 革砥

Leather strop used for final finishing a sharpened edge.

Kawa – カワ

The “skin” of a whetstone, the hard natural outer surface of raw sediment.

Keppan -血斑

Blood Spot. Often used to describe a red splotch of color in a Kiita Toishi.

Kesuji – 毛筋

These are hairline inclusions that are safe to hone on. They contain soft particles that will not damage the edge. They can take on water though, and over time they can cause the stone to split along the line.

Kiita – 黄板

Yellow Plate.  A stone showing a yellow coloration is called Kiita.  They are highly sought after, and are generally seen being a bit softer than most Asagi stones, but some Kiita are exceptionally hard. Kiita often have Nashiji as well.

Kiridashi – 切り出し

This slang term refers to the leftover pieces of Koma that are smaller than “Hikikoro”; their weight is usually around 80-100 g.

Kiiro – 黄色

Yellow/Amber. Usually used to identify qualities of a stone but not the whole stone itself, otherwise it would be noted as Kiita.

Kizuyama – 木津山

One of the eastern whetstone mines in Kyoto.

Koma  – コマ 

Fine. Koma Nagura is the finest and usually the most expensive of the Mikawa Shiro Nagura. In a sword polishing progression, Koma follows Chu, and it is the last step before the final polishing steps. Some debate exists whether Koma is actually finer then Mejiro. It leaves a finer polish regardless of the answer.

Kongo Do – 金剛砂石

Emery Whetstone. This is most often the first and coarsest stone used in sword polishing. An approximate grit rating could be 80-220x. This is primarily used for the rough shaping of a sword’s geometry, or heavy repair work.  

Koppa – 小端

Small End. This term is used to describe a larger or small stone with an irregular shape.  It is often used to describe a small razor size stone also. Koppa are usually less expensive options than their bench-stone sized brethren. 


A relatively unknown stone which is medium-fine, a bit rougher than Aizu.

Koukyuu – 高級

High class or high grade. 

Kouzaki – 神前

This was a mine in the Tanba area where Aoto were quarried; the stones from this location were generally harder and finer than stones from the other mines, acting as Awasedo stones rather than Nakatoishi.

Kuro – 黒

Black. Usually used as a stone characteristic for Tsushima or other very black whetstones.

Kyoto – 京都 or 京都府

Kyoto-Fu. Kyoto is a prefecture in Japan that is located in the Kansai region on the island of Honshu. The capital city is also named Kyoto. The prefecture of Kyoto is where many of the most famous whetstone mines were located.

Kyoumen-Shiage – 鏡面仕上げ

Mirror Finish.  This is a self explanatory term used to describe a very high polish on the bevel. 

Kyou-To Toku-San – 京都特産

Special Product of Kyoto. A stamp seen on the tops of Tennen Toishi.  

Kyushu – 九州

A Japanese region/island. Amakusa & Binsui Toishi, and Tsushima Black Nagura are quarried here.

Marine Steel – 舶来鋼

Marine steel is an alleged ‘rust resistant’ variant of Carbon Steel, often said to be a precursor to stainless steel. It wasn’t very rust resistant though. Often incorrectly called ‘imported steel’, which is the Chinese translation of the Kanji. 

Maruichi – 市印

Maruichi jirushi. Maruichi brand.

Tokusen – 特撰

Especially Selected. There is a story claiming that this stamp was used by Kato-san when he ran the quarry at Nakayama.  There is another story claiming that not all stones with this stamp are from Nakayama. For whatever reason – there doesn’t seem to be any hard data on this stamp’s origin, use, or history. 

Maruka – ㋕正本山         

Maruka Shou-Honyama. A stamp that is found on the ends of stones quarried at Nakayama. This was used by Hatanaka, the circled ‘Ka’ character paid homage to Kato-san, the previous owner of the mine. The translation of ‘maru’ is circle; the circled Ka translates to Maru-Ka or Maruka. the rest of the characters are Shou-hon-yama which mean ‘Real Original Mountain’. 

Masame  – 柾目

Straight Grain. Japanese whetstones cut across the grain, so the lines show on top of the stone’s working surface.

Maruoyama – 丸尾山

A western mine in the Oouchi district; known for stones quarried from the Hon-Kuchi and Ai-ish Naori. They have 3 quarries at Maruozan (丸尾山) mountain. This mine is still active.

Mejiro – 目白

White Eye. This is a mid-range Mikawa Shiro Nagura. There is debate about whether this is finer than Koma or not. It should precede it based on tests of final polish regardless of absolute fineness though.

Mikawa Shiro Nagura – – 純三河白

These Nagura are quarried in the Aichi prefecture at the Mikawa Nagura Mine. When honing razors, these stones are used to create an abrasive mud or slurry on a harder finishing stone. Mikawa Nagura can also be found cut as full-sized bench stones, these are used for polishing swords, and sharpening many types of edged tools, including razors. 

There are 12 layers of stone at the mine, but only 8 can be used for sharpening. Ban, Mushi, Atsu, Yae Botan, Botan, Tenjyou 1, Tenjyou 2, Mejiro, Koma. For honing razors, the most commonly used are Botan, Tenjyou and Mejiro. Koma is also used for razors but less frequently; it is very rare and expensive. Historically, the finest quality stone from Mikawa carry the Asano quality stamps. 

Usually, stones will not be marked with the – 純三河白 kanji but instead the Junzo Kawashiro Nagura – 純三河白名倉 kanji

Mizu Asagi – 水浅黄

Water Shallow. Usually, this term is used to describe a blue/grey color that is reminiscent of shallow ocean water. The color can also be greenish as well and is formed between Asagi and Kiita layers. These stones typically have a high percentage of grit within them, resulting in the white of the silica the mixing with the grey (Asagi) and yellow (Kiita) creating the color.

Mizukihara – 水木原

A western Kyoto mine, located in the same mountain as Ohira.

Mokume – 木目

Wood Grain. A pattern that resembles the grain found in wood.     

Momiji – 紅葉

Autumn Leaves. Often said to be specifically maple leaves. This is a pattern that looks like leaves in/on the stone. Many say it is specific to Suita stones, but it has been used to describe a leaf pattern on Tomae stones also. An alternate term is Kouyou.  

Mushi – ムシ

No distinct translation. This is the second course Mikawa Nagura, one of the usable layers of stone that are quarried. Generally used for sharpening edged tools along with Ban.

Nagura – 名倉

Correcting Stone. This can mean any stone that is rubbed on top of another stone to create slurry or to smooth out one or both surfaces. See Tomo Nagura, Chu Nagura, Mikawa Nagura and Diamond Nagura.

Nakado – 中目

Also referred to as Nakame. It means middle grain.

Nakatogi – 中都議

Medium Polish. This term seems to be used mostly in the carpentry trade. It refers to the middle stages of sharpening, up to and including the pre-finish sharpening.  

Nakatoishi – 中砥石

Medium Grain Whetstone. Can also be referred too as Chu-Shiage Toishi. These stones are used for the mid-range sharpening/polishing work, which is relative to the type of edge being developed. When sharpening swords and other heavier cutting tools, Kasei, Binsui, Chu Nagura Do, Uchiguimori and Koma Nagura Do are commonly used as Nakatoishi.

Namito – 並砥 or 并砥 or 大上

This is a deep strata in the Hon-Kuchi naori. It is located below Aisa and above Hon-Suita. These stones are often hard, fine grained and very consistent quality. Less likely to have inclusions. 大上 is the lower portion of the Namito layer referred to as Daijyo but is usually all lumped together under Namito.

Nakayama – 中山

This is arguably the most famous eastern whetstone mine. It was located at Atago Mountain.

Namazu – なまづ or 癜

Catfish. This is a pattern seen in Japanese natural whetstones. It is usually comprised of irregular lighter-colored blotches, streaks or spots on the surface. 

Nan – 軟

Soft. One of the Kōnan-do Kubun (硬軟度区分) or hardness classifications.

Naori – 成り

Strata. See Hon-kuchi, Chu-ishi, and Ai-ishi Naori.

Narutaki – 鳴瀧 or 鳴滝

This can refer to the mine, or the region where the Higashi Mono or Eastern Mines are located. 

Nashiji – 梨地 or なしじ

Pear Like. This is a pear skin pattern found mostly on Kiita stones from the Tomae strata.  Many believe that Nashiji indicates superior cutting speed but whetstone authorities claim it is only a visual aesthetic. It looks very similar to Goma but brown instead of black.

Nihon Kamisori You – 日本剃刀用   

For Use with Japanese Razors – a stamp seen on the top of vintage finishing stones.

Nishi no Yama  – 西の山

Mountains in the West. Refers to the western mines of Kyoto, e.g. – Tanba, Ohira, Mizukihara, Shinden, Okunomon. 

Nenrin Hada – 年輪肌

Annual Rings Skin. This term is used to describe a detailed pattern that looks like the growth rings seen when you cut through a log or tree.


Also sometimes called Numata also sometimes called Tora-to. A mine closed in 1965 from Gunma prefecture. It is finer than other stones from Gunma.

Ohira – 大平

Sometimes written as Oohira. A western Kyoto whetstone mine, well known for Awase, Suita and Uchiguimori. This mine is still active.

Okudo – 奥殿

This is a eastern (Higashi Mono) Kyoto whetstone mine that is best known for the most highly coveted Suita in Japan. This mine is still active.

Okunomon – 奥ノ門

This western Kyoto mine was located next to Ohira.

Omote – 表 

The signature side of the sword’s nakago, it is the obvious side of the blade that faces away.  

Omura – 大村

A whetstone mine on Kyushu, this location was known for producing sandstone Aratoishi. 

Otoyama – 音羽山

This whetstone mine is known for producing Suita.

Ōuchi – 大内

A Western Mine known for softer coarser bench stones of good quality. 

Ozuku – 大突

This was one of the famous eastern mines in Kyoto.  

Ozaki – 尾崎

A whetstone mine in Kyoto. 

Renge – 蓮華

Lotus Blossom. This coloring/patterning is specific to Suita stones. Usually seen as a red, orange, pink patterns of fine freckling within the stone. Black Renge has its own name and is referred to as Enshou. This visual aesthetic has no positive affect on sharpening capabilities; some say that the presence of Renge indicates a reduction in cutting strength. Not to be confused with Goma or Nashiji, which will be clear dots rather than various shapes.

Ring Roll – 环卷

A stone with circular patterns on it, or colors that form ovals within it’s surface.

Saeki – 佐伯

This location is known mostly for the production of soft coarse stones. Some examples are harder and highly sought after.

Sai Jou Kyuu – 最上級

Highest-grade. This stamp can be found on finishing stones. 

Saiku – 細工

Craftsmanship. Can also mean trick.

Saiku Hira Kanna – 細工平鉋

Plane for very fine work.

 San  -サン

San size is a form-factor for Japanese Natural Whetstones. They are long and thin, usually around 200 x 50mm or similar. Often, these San-size Toishi are end cuts removed from larger slabs that were portioned into full-size bench-stones.  

Semai- 狭い  


Senmai – 千枚

2 seams of strata. Sometimes compared to performing as a mix between Suita and Tomae, but it is also often a fairly compressed, hard, and fine stone still. Though it may have Suita properties in the stone face feeing silky/soft, it tends to be fairly hard and not lend itself easily to polishing work – instead being better for sharpening knives/razors. Due to how thin the layering was, it is very rare to find large stones from this strata.

Shiage – 仕上げ

Finish. These are the final stages of sword polishing.  

Shiage To – 仕上砥

Finishing Grit Stone. One of the Ryūdo Kubun 粒度区分 or Granularity Classification.

Shiage Toishi – 仕上げ砥石

Finishing Stone. These stones are usually fairly hard and fine – and may be the last or second to last stone in the progression depending on objective. They are not as fine grained as Awasedo. This is not a firm rule, and sometimes seems to be interchangeable with Awasedo.

Shimari-gimi – 締り気味

Tight Feeling of Interference. This term is used to describe the hardness of a whetstone that is above average hardness, but not quite ‘very hard’.

Shin Tsū – 普通

Common. One of the Kōnan-do Kubun (硬軟度区分) or hardness classifications.

Shinden – 新田

A Western Kyoto mine known for producing highly prized Suita.

Shinogi – 鎬   

This is the ridgeline on the blade where the Mune meets the beveled Ha.

Shiro – 白

White. Usually used to identify qualities of a stone but not the whole stone itself.

Shiro Suita – 白巣板 or 白巢板

These deep-stratum Suita are usually hard, fine and fast. They are exceedingly rare, highly coveted and very expensive. Not all white Suita are Shiro Suita, it must come from the specific strata.


This whetstone mine is connected to Ozuku.

Shitaji – 下地

Ground Material. These are the lower stages of sword polishing.  

Shou Hon Yama – 正本山

Real Original Mountain. This stamp can be found on finishing stones.  Also reads as Shou – Hon – Zan.

Shouhonyama 正木山 or Shouhonyama Honkakuhin – 正木山木 格品

Correct Original Mountain Original Source. This is often mis-translated as Masamotoyama. This should infer that the stone comes from the area around Kyoto where the original Honyama were mined.

Sikiutigumori/Shikiuchigumori – 敷内曇

Clouds on the Floor. Similar to the Karasu pattern, but instead of angular crow-like shapes it will have a cloud-like appearance within the grain.

Stratum – 層

A layer of whetstone; Tomae and Aisa are two strata in the Honkuchi Naori.

Su – 巣

Nest. These are small holes that were left behind by escaping gases when these stones were being formed in the earth’s crust. They are associated with Suita stones, but they can be found in other layers also.

Suita – 巣板 or 巢板

Nest Plate. Suita stones come from 3 different stratum.  Most, but not all, of them have ‘su’ – small holes or pockets created by escaping gas when the stones were forming in the earth’s crust.  Under close inspection,  su can resemble a hive or a nest. Suita without su are known as Sunashi Suita.

Suji – 筋

Muscle. This refers to lines in the hone, some of which may be safe while others can be toxic Kesuji and Kanesuji.

Sujimono – 筋物

Muscle Of. This word references stones with a lot of Suji. Often, but not always, this characteristic is an indicator that the stone is inferior.   

Suminagashi – 墨 流 し

Black Ink Flow. This is the process of marbling paper with ink or dye that is floated on water. A stone that has a similar type of pattern may also be referred to as Suminagashi.

Sunashi – 巣なし

No Nest. This is a type of Suita stone that has no su.

Sword Grade – 刀剣用

Sword with Knife. This Asano quality stamp can be found on large pieces of Mikawa Shiro Nagura; it infers that the stone is high quality and good for use when polishing swords. 

Tamago – 卵 or Tamagoiro -卵色

Egg. Used to describe the color of stones with a specific type of mottled creamy yellow coloring.

Takao – 高雄

This whetstone mine in Kyoto was well known for producing Awasedo.

Tajima-To – 但馬砥

Also called Tajimado. Medium-fine grit whetstone. Not very popular around Japan but a very good whetstone from Nishihama, Mikata, Hyogo.

Takashima – 高島

This whetstone mine is located northeast of Kyoto. Stones from this location come from the Hon-Kuchi Naori, and they are generally very consistent and fine but a bit soft.

Tamahagane – 玉鋼

Iron Sand Steel. A type of steel used by master sword smiths in Japan. Some classic Japanese razors will be marked as having this steel, though not entirely accurate (see Yasuki Steel below).

Tamamoku – 玉目

Circular Burls. This is a rare and beautiful Toishi pattern that emulates the figuring in Tamamoku cedar.

Tanba – 丹波国

Tanba no kuni. This was an old province in Japan, this area is where many Aoto Toishi were quarried. Sometimes spelled “Tamba”. 

Tamba Kei – 丹波系

Tamba family. Refers to the general area where stones are quarried in and around Tanba. 

Tengu-do – 天狗砥

Tengu whetstone. This is a coarse stone with red stripes. It is similar to, but more aggressive than, Amakusa white.

Tenjyo – 天上

Heavens or Sky. A mid-range Mikawa Nagura, also spelled Tenjyou or Tenjō.

Tenjyou Suita – 天上巣板 or 天上巢板

A shallow strata or layer in the Hon-Kuchi Naori. 4 main seams including Uchigumori, nagagumori, sotogumori, and a type of Shiro (white) Suita.

Tenjyou Tomae

A stone strata located in the Ai-Ishi Naori.

Tennen Toishi – 天然砥石 

Natural whetstone.

To – 砥

Whetstone or Grindstone. 

Togidoro – 砥泥    

Stone slurry mixed with steel. May also be known as swarf .

Tojiru -閉じる

This term refers to the lubricating abrasive paste, or slurry, made with Uchiguimori. It is often loosely translated to mean ‘juice’, when referring to any slurry on any Tennen Toishi.

Tokusenhin – 特撰品

Choice goods. This stamp can be found on some Tennen Toishi.

Tomae – 戸前 or 户前

This is the largest strata in the Hon-Kuchi Naori; there are 48 veins of Tomae.  It is found above the 4 layers of Aisa, and below the 2 layers of Senmai strata.

Toishi – 砥石


Tokkyuu – 特級  

High grade. One of the Asano quality stamps used on Mikawa Nagura; it indicates that the stone is striped with an odd shape.

Tokkyujou – 上特級

Superior High Grade. One of the Asano quality stamps used on Mikawa Nagura; it indicates that the stone is striped with a square shape.

Tomen – 砥面

Abrasive surface. A whetstone’s working surface.

Tomo Nagura – 共名倉 or ともなぐら

Companion Nagura. This is a nagura you use on a whetstone which is the same material as the whetstone itself. To be a tomo nagura, the nagura must be cut off the whetstone itself or from the same mother block the whetstone was sourced from. The use of this generates slurry of all the same type.

Tomoto Kyho Togi – 共砥

Co-Abrasive. Also translates to Paired Hone.

Torato – 虎砥

Tiger Whetstone. This term is often used when referring to Amakusa Toishi that have reddish ‘tiger’ stripes. 

Tsushima – 対馬

A whetstone quarried on the island of Tsushima, off the west coast of Nagasaki. It is a mid-range whetstone that produces slurry that breaks down to a very fine degree. There are two types of Tsushima Black, Ocean and Mountain. The Ocean Tsushima Black is quarried underwater. The mountain version is very coarse, brown and held in low regard.

Type 30

A Type 30 Japanese natural stone indicates a minimum size of 205mm (L) x 75mm (W) x 30mm (H).

Type 40

A Type 40 Japanese natural stone indicates a minimum size of 205mm (L) x 75mm (W) x 25mm (H).

Type 50

A Type 50 Japanese natural stone indicates a minimum size of 180mm (L) x 82mm (W) x 30mm (H).

Type 60

A Type 60 Japanese natural stone indicates a minimum size of 195mm (L) x 70mm (W) x 25mm (H).

Type 80

A Type 80 Japanese natural stone indicates a minimum size of 180mm (L) x 63mm (W) x 20mm (H).

Ukeai Junshou Honyama –  請合純正本山  

Guaranteed Real Nakayama. This stamp can be found on the top of whetstones.  

Uchiguimori – 内曇 or 天上巣板 or 天上巢板

A specific type of Suita that is traditionally mined at Ohira. There are two types, Hato and Jito; they are used for bringing up the polish to accentuate the Hamon on a sword or the steel’s patterning on a knife. Often used as Hazuya.  

Uchigumori Hato – 内曇刃砥         

This softer Uchiguimori is used to bring out details in the Ha. 

Uchigumori Jito – 内曇地砥

This harder Uchiguimori  is used to bring out details in the Ji.


From Gunma, it is a medium-fine whetstone similar to Tajima-to.

Umaji – 馬路山

This Nishi-mono whetstone mine was located on the west side of Mt. Atago along with Oohira and Shinden. Generally, but not always – this location was known to produce softer stones from shallow layers. 

Umegehata – 梅ヶ畑

A valley area in Kyoto Japan, Nakayama and other famous mines were located here.   

Uma Kawa – 馬皮



These whetstones are quarried in Unzen, Kyushu. They are very similar to Amakusa whetstones and fall between the red and white versions of those stones. It suffers the same issue of an uneven grain structure. This mine is still active.

Ura – 裏

The secret side of the sword that faces inward, toward the body.

Wakasa – 若狭 

This is a whetstone mine at Miyama Mountain. Some Wakasa are very hard and fine, but many are a little bit soft. 

Yaginoshima – 八木嶋  or 八木ノ嶋

This whetstone mine is located east of Ohira and known for producing good Suita.

Yake – 焼け or やけ

Burnt. This is a dark orange/deep umber coloring often seen on Suita but can be present on any Tennen Toishi. When and area of stone shows very dense and hard Yake, it can be problematic to hone on and it can scratch the blade. This word is also used to refer to any pronounced splashes of color on a stone. 

Yakiba – 焼き刃  

Tempered Blade. This is a sword term; it refers to the hardened, tempered area from the top of the Hamon to the edge

Yari Kanna – 鑓 鉋

Japanese woodworking plane.

Yasuki Steel – ヤスキ鋼

YSS is a special designation given to specific steel types produced by Hitachi. Some razor manufacturers have referred to these steels as ‘Tamagahane’.  I have to assume that this was done, mostly, during a period of time when very little real Tamagahane was being manufactured. While YSS was created using the same iron sand, it is not Tamagahane steel; it can be White 1/2, Blue 1/2/Super or Yellow Paper steel. Because Yasuki/Yasugi steel is made in Japan, it is referred to as Nihontetsu 日本鉄 . 

Yae Botan – 八重ボタン   

Eightfold Peony. It is eightfold due to being the eight usable layer. A medium-coarse Nagura quarried at Mikawa. This layer is known to sometimes have sand layers and quartzite inclusions. These Nagura were usually faster and coarser than Botan. 

Yuge – 弓削

This is a whetstone mine in northern Kyoto. This source is known fo softer high- quality stones from Tomae strata; 弓削 戸前 = Yuge Tomae.

Yuuryou Shiage To  –  優良仕上砥 

Superior Finishing Hone. This quality stamp can be found on Awasedo.