Japanese Natural Stones

Ohira Renge Suita (front)

I've used a very few Japanese natural stones for sharpening kitchen knives before I decided on buying one for myself. I am no expert in these type of stones. I believe it takes years of trying out different stones and meeting mine owners and knife experts to truly grasp the ins and outs of natural stone sharpening. It is a rabbit hole too deep to fully understand in one sitting.

Natural stones used for sharpening are almost 100% quarried off of Japanese mountains. They are classified and named based on what mine it was dug from, what appearance it has and what particular strata it belonged to underground. They can be very confusing at first but eventually, you get to hear about good mines and good stones from other knowledgeable sellers and enthusiasts. When you're starting, your best way to get and understand these types of stones is to talk with fellow sharpening enthusiasts. You won't know what you need or want without consultation.

Ohira Renge Suita (back)

Then there is the question on whether you need it or not. Personally, because of the ridiculously high prices, I don't think you need one. It's just better to have one. The main quality that a natural stone has over your synthetic stones is that particles are more or less uneven and its properties provide a beautiful finish especially for kasumi finishes on traditional Japanese knives or wide double bevel knives. With its uneven particle nature, you get an uneven height serration on your knives promoting better edge retention since your edge won't dull all at the same time. You pay a ridiculously high premium to get this. Let me put it like this: you get 85% of your knife's potential using synthetics. The next 15%, you get from naturals. This doesn't mean you need it. Your knife will still be sharp as hell with your King stones or other synthetic stones. Again, it's just awesome and great to have one.

Let's say you've decided on getting one for yourself. In the natural stone business, you get what you pay for. It's like buying a traditional Japanese knife. The less you pay for it, the more likely you're getting a low quality blade. In this case, quality is very much apparent. You would want to get a good one first, before you spend a lot of money on different low quality stones. You'll find yourself with a lot of stones but only use one or two good ones. It can get addicting, so my advice is to get a quality stone that you'll use for years. Again, you don't need one but if you're getting one, you only need one (if that makes sense).

Tomo Nagura

Natural stones do not have any grit number. You can only get a stone's impression by asking a person who has tried it. Jnats also might change coarseness during sharpening. It just depends a lot on pressure and an expert's first impression. Start by getting a nice finishing stone with good size and height from a reputable source. I can give you some sources if you ask. It is also important to talk with the seller or supplier about the stone and discuss your purpose. There are a lot of fake stones out there so don't go buying your first Jnat from ebay. Also get help in determining if your stone needs to be sealed from moisture or not. Again, a qualified expert can tell you this.

Use your new Jnat and learn all about it (believe me, this takes time). No two stones are the same. Learn how to control the slurry produced by your new stone and remember that pressure is key. You may want to reduce pressure as you build more slurry when polishing your blade (it depends on your purpose) and consequently add more when trying to raise a burr.

These are just quick guidelines in diving into the world of Japanese natural stones. I just touched the tip of the iceberg. If you plan to try and learn more about these fascinating sharpening stones, there are a number of people online who can assist and guide you more. There are also a lot of videos online for this too. The knowledge and information is unending and the price is worth it.