Diamond Whetstones are More Than Just For Sharpening Knives

Diamond boasts the highest hardness of all materials out there. This might make you think that a whetstone using it will sharpen very well as a result, but are there any disadvantages to this whetstone? Nothing is perfect, and this article will help you delve into the world of whetstones using the hardest material on the planet.

What is a diamond whetstone?

The whetstones we see on the market today are normally made using abrasives we refer to as "general abrasives". Where diamond whetstones differ is they use a diamond-based material referred to as a "super abrasive".

Diamond is the hardest substance we have on this planet, which makes whetstones using this material significantly harder than other kinds of whetstone.

These whetstones were originally made as industrial whetstones - not commonly used for kitchen knives. However, because of the unique characteristics these whetstones have, various whetstone manufacturers advanced technologies over the years and made them more commercially available and viable, leading to their now-popular state in the culinary world.

Special features of diamond whetstones

Diamond whetstones are in some ways more flexible and useful than some other kinds of whetstones. Some examples are listed below:

No wear on the whetstone

The main issue with normal whetstones is that they are finite, and wear down as they are used over time. Since these whetstones almost always don't wear down in a level fashion, a concave is created on the stone. This means the whetstone needs to be resurfaced to keep its usefulness.

Diamond whestones circumvent this issue thanks to their harder abrasive grains. They don't wear our nearly as much as other whetstones, with some saying they will always maintain their flatness. This makes them perfect for not just sharpening, but other uses we will get into later in this article.

High polishing ability

The diamond abrasive grains in these whetstones are not only extremly hard, they're sharp and protrude from the whetstone's surface.

The result of this is a significantly higher grinding ability, meaning diamond whetstones will sharpen very effectively.

Types of diamond whetstone

As stated earlier, diamond whetstones are made by hardening diamond abrasive grains. This is done via one of two methods - electrodeposition and sintering. Select the appropriate tab to see each difference with a table beneath that showcases the advantages and disadvantages.

Electrodeposition method whetstones are made by plating then attaching diamond abrasive grains to a base metal's surface. In this case, the protrusion of the abrasive grains is high as well as the general abrasiveness of the stone, giving this stone a very high polishing power. These stones are also easier to make compared to their counterpart, which lowers their price.

However, these grains are only attached thinly during the stone's creation, which means they often peel off during use. The layer of diamond is also thin, which means after some polishing it can be easily removed. It does also cause deeper sharpening scratches after polishing, so removing those requires more work.

Sintering method whetstones are made by baking diamond abrasive grains and a binding agent at a high temperature and pressure. This allows for much thicker layers to be used on the stone, granting it a much longer lifespan. This stone can be used in a very stable fashion as there's less worry about the layers peeling off.

Another benefit of sintering stones is their variety, being available from rough stones all the way to finishing stones. However, this comes with the downside of the polishing power of these stones being inferior to electrodeposition whetstones. In turn though, this does mean the sharpening scratches it leaves behind are more shallow, making it easier to remove them with the next whetstone in the process. Plus, this stone holds its flatness well, so if it's a finishing whetstone, it's very good for "back pressing" technique, a mandatory part of sharpening.

A key downside is the price - these are simply more expensive to produce, so cost more for the consumer to purchase in turn. The thicker layers do also lead to occasional clogging and wear and tear, so resurfacing and cleaning are more necessary.

Stone Type Ups and Downs


+ High polishing power
+ Inexpensive

- Deep scratches
- Short lifespan


+ Longer lifespan
+ Wide grit range
+ Shallow scratches
+ Holds flatness

- More costly
- Less polishing power
- Can get clogged
- Needs maintenance

Consider what merits are important to you and how you sharpen before choosing a diamond whetstone

Using a diamond whetstone

While of course this whetstone can be used for all kinds of sharpening due to the large variety of grit numbers, we've specified three key examples where diamond whetstones shine:

Flat Sharpening

Because of the characteristics of diamond whetstones: hard, flat, and highly abrasive, the best use of a diamond whetstone is flat sharpening, which sharpens the blade flat. This sharpening method is used when sharpening the blade road (the part from blade ridge to blade edge) of Japanese knives. See a picture below for what we mean by kireha.

Blades (especially Japanese ones) are generally hard, so when sharpening with a diamond whetstone, the contact area is very narrow because both objects are hard, creating a point-by-point style sharpening. Sharpening this way will lead to these points expanding and spreading out, creating a solid and flat cutting edge.

Ideally, a knife should be sharpened to what we call a "clam-shell edge", but in rare cases when you sharpen to this state it can make the blade round and thick. A diamond whetstone works perfectly to fix this.

These whetstones are also great for carpentry tools like planes and chisels, which always require sharpening of the blade road.

Fixing the back of a Japanese knife

Some kinds of knives always need a specific kind of sharpening in order to bring out their maximum potential. Single-edged Japanese knives are a strong example of this, requiring "back pressing" in order to properly reach a sharpened state. Doing this requires a very flat sharpening surface - something diamond whetstones excel at always having. So these can be good for very specific sharpening steps.

Resurfacing a whetstone

Diamond whetstones are also perfect for resurfacing other whetstones.

While resurfacing whetstones exist, those in turn also wear out over time much like a whetstone does. While it would be fine if these wore out evenly, also much like whetstones they'll develop a concave over time, in turn meaning they need resurfacing. This creates an endless loop of sorts. Thanks to the flatness of diamond whetstones however, this can be easily circumvented. Resurfacing using a diamond whetstone allows for a very high degree of accuracy in creating a whetstone that is level, which can be used optimally.

While we don't sell diamond whetstones on our website, we can supply them and do sell them in-store. Reach out to us with a message if you are looking for one and we can help you out.