Written by Maksim
Why Use Natural Stones?
I get this question a lot. People ask — why spend more on a natural stone when synthetics are cheaper and easier to find ? Here is my honest answer from my experience.
Sharpening particles in natural stones are uneven in size. The edge you get has uneven "teeth" too. This is not a problem — this is the point ! Those uneven teeth dull at different rates, so the knife stays sharp much longer than an edge from synthetic stones. Also natural stones dish very slow compared to synthetics. A good natural stone can last a lifetime and almost never needs flattening.
Natural stones also remove burr easier than synthetics, so you can get the knife much sharper. And if you use them right, you get a hazy kasumi finish on the jigane that looks fantastic and is impossible to get with synthetic stones.
I am a chef and I use my knives a lot. I can feel the difference clearly when a knife is sharpened on natural vs synthetic stone. It is not placebo :)
|
Stays sharp longer Uneven teeth dull at different rates — edge lasts much longer than synthetic. |
Lasts a lifetime Dishes very slowly. A good stone will outlast any synthetic by a lot. |
Removes burr better Deburrs more effectively — you get a finer, keener edge. |
Kasumi finish Creates the beautiful hazy kasumi that only natural stones can give. |
How to Select a Stone
This is the most important thing to understand before you buy anything.
In general, softer natural stones are more useful for kitchen knives and easier to use than harder stones. It is best to start with softer stones and get harder stones as your skills improve. Some very hard and fine stones can scratch soft iron (jigane) but not hard steel (hagane) — that is not because the stone is bad but because the steel is softer than the stone particles ! So you have to use hard stones with care and only with slurry and light pressure.
Also — mine name (Nakayama, Ohira), strata (Namito, Aisa), brand (Maruka)... these are just selling words. I have tried many stones and none of these names guarantee you a good stone !!! Some are very expensive just because of the name and not because of performance. I tried a Maruka for 2000 USD that performed similar to an Atagoyama for 500 USD same size. So do not fall for this.
Quick guide by what you are sharpening:
- Kitchen knives, beginner: Lv 1.5–3 — soft, fast, forgiving, easy to learn on
- Kitchen knives, advanced: Lv 3–4 — finer finish, good kasumi results
- Ura on single bevel tools: Lv 4+ — hard stone for the flat back, less risk of scratching hagane
- Razors, beginner: Lv 3–3.5 — learn slurry and pressure on this before going harder
- Razors, advanced: Lv 4.5–5 — very fine edge, requires correct pre-polish and experience
The JNS Rating System
Every stone on JNS is rated with four things. What matters most is that the stone works on your knife or razor — but here is how to read the description:
| What | Meaning | Example |
|---|---|---|
| Mine | Where it was quarried in Japan | Nakayama, Ohira, Ozuku, Shoubudani |
| Strata | Geological layer — softer on top, harder below | Tomae, Namito, Tenjyou, Suita |
| Appearance | Color and visual character of the surface | Asagi (grey-blue), Kiita (yellow), Karasu (dark spots) |
| Level (Lv 1–5) | JNS hardness — Lv 1 softest, Lv 5 hardest | Lv 2 = knife stone, Lv 5 = razor finishing stone |
So a full description reads: Ohira Tomae Lv 2, or Nakayama Asagi Lv 4, or Shinden Suita Renge Lv 3.5.
| Lv 1 | Softest — fast cutting, easy slurry. Beginners and coarse work. | |
| Lv 2 | Soft — great all-around knife stone. Raises slurry easily. | |
| Lv 3 | Medium — kitchen knives and light razor prep. Good finishing stone. | |
| Lv 4 | Hard — razor pre-polish, high end knives. Needs experience and nagura. | |
| Lv 5 | Hardest — razor finishing. Very fine. Only for experienced users. |
The Mines
Almost all mines in the Yamashiro region near Kyoto closed 60–70 years ago. The only quarry still sometimes active is Maruoyama, and very rarely Ohira. All current stock comes from raw material dug out before mine closure and stored by wholesalers like Tanaka, Imanishi, HaTanaka and Asano.
Stone quarrying in the Yamashiro region near Kyoto. Most mines closed around 60–70 years ago.
| Nakayama 中山 | Ohira 大平 | Ozuku 大突 | Shoubudani 菖蒲谷 |
| Okudo 奥殿 | Shinden 新田 | Mizukihara 水木原 | Atagoyama 愛宕山 |
| Hakka 八箇 | Kouzaki 神前 | Yaginoshima 八木ノ嶋 | Nartuaki 鳴滝 |
| Okunomon 奥ノ門 | Otoyama 音羽山 | Wakasa 若狭 | Saeki 佐伯 |
Things People Get Wrong
Kiita stones are not always the best
Yellow (kiita) stones are popular because you can easily see the swarf and progress. But hard gray Asagi from Nakayama, Shoubudani or Ozuku are just as good. Iwasaki-san who makes top kamisori razors did experiments and found no difference in result between bright yellow and gray stones. Only the price was different !!! Kiita stones are now almost gone and extremely expensive. There are also many soft kiita that are not useful for razors at all.
Appearance does not give extra sharpening power
Karasu, Renge, Nashiji... they are beautiful and often rare. That is why they cost more. But they do not give any extra cutting ability over a plain looking stone. Do not buy a stone only because it looks beautiful — buy it because it works for what you need !!!
Hard stones are not bad for knives
Some people say hard stones are bad for knives. A person who claims that has very little experience with Jnats. Hard stones can scratch the soft iron cladding (jigane) if you use them wrong — no slurry, wrong pressure. That is a technique problem, not a stone problem. You have to use them with slurry and light pressure. Very hard fine Jnats can produce outstanding kitchen knife edges when used right.
Hard stone giving bad results? Usually technique, not the stone
The biggest problem I see — people do not do enough pre-polishing before moving to a hard finishing stone. A hard Lv 5 stone is so fine that on the first passes it reveals scratches from previous coarser stones. They see scratches and think the stone is not fine. But the hard Jnat is extremely fine — they just did not finish properly on the stone before. Best use for hard stones on a knife — only with nagura and slurry, and only after you have finished the previous step well !!!
On Nakayama prices and fake stones
Right now Nakayama Kiita and Suita stones are selling for very high prices. This leads to some vendors selling stones from other mines as Nakayama. Some sellers in the US are selling Ohira stones as Nakayama. Some will claim they can tell a stone's mine origin by looking at the skin — this is rubbish !!! I have asked many stone experts in Japan and they all agreed it is very hard to tell even for an expert. Only by testing the stone.
Why Harder Stones Need More Experience
The harder the stone, the harder it is to raise slurry. On Jnats the slurry does the work — if you cannot get slurry you will get no result at all. At the same time super hard stones are also the finest and best for razors. To get the most from a very hard razor stone you need to understand how Jnats work, slurry breakdown and polishing characteristics. Start with a softer stone, learn how it works, then move to a harder one and you will experience the finest edges there are.
Video: Ozuku Lv 5 with Mejiro Nagura — how nagura speeds things up on a hard stone
That's it for now :) More updates coming with new photos and videos. If you have questions just message me directly — WhatsApp is fastest.