What gives the Belgian whetstones its exceptional sharpening characteristics?

The Belgian Whetstone consists of 30 to 42% garnet crystals bonded together with mica. These garnets are what give the Coticule its exceptional sharpening characteristics. The geometrical shape of these garnets is a dodecahedron. There are twelve surfaces with obtuse angles. The garnets have a diameter of 5 to 15 microns and penetrate 1 to 3 microns into the metal to be sharpened. This ideal geometric shape (obtuse angles polish the metal) and the large numbers of these garnets ensure that the blade is sharpened both very quickly and extremely finely. In just a few minutes, this results in a razor-sharp cut, for any object that is to be sharpened.

A large variety

The Belgian whetstone is often compared to a 4000 - 8000 grit whetstone, using the Japanese grit system, but it must be borne in mind that it is a  natural product, and therefore no stone is 100% identical to another. The grit rating is given purely for information, and tells you little about the specific characteristics of the stone. The advantage compared to other whetstones is: A Beglian whetstone sharpens very finely and very quickly. No other whetstone possesses this combination.

The hardness of the garnets ensures that they are able to hone any kind of steel, including stainless steel (inter alia, 18/8 and 18/10 stainless), Damascus Steel and HSS High Speed Steel.

The geometric shape of the garnets gives the whetstone another unique characteristic. The smooth shape of the garnets means that they sharpen the metal without leaving behind tiny burrs.  This results in a fine gleam without scratches on the blade, which makes the knife considerably easier to use.

A few examples:

1. A razor sharpened with a Belgian whetstone does not damage the skin during shaving. The garnets do not leave any tiny burrs on the blade, which is unique to the whetstones!  This means that there is no chance of skin irritation! The Belgian whetstone gives a razor-sharp blade and unrivalled comfort during shaving. Without skin irritation, the skin feels very soft after shaving.

2. Kitchen knives, hunting and pocket-knives keep their sharp blade for a long time, and can be made razor sharp in the twinkling of an eye.

3. The blade of all kinds of tools such as chisels, gouges and axes is polished so finely that materials like wood fibres are cut through quickly and cleanly, resulting in a smooth finish. There are no nicks in the surface. This is why the stone is sought after by carpenters and sculptors.

Various fields of application of the Belgian whetstones range from razor blades, all kinds of cook's and kitchen knives, hunting and pocket knives to chopping and cutting tools.


A Coticule whetstone consists of 2 layers. The Coticule top layer has a thickness of between 5 and 10 mm, depending on the Coticule seam (not every Coticule seam in our quarry is of the same thickness). This Coticule layer is glued on a substrate of unusable black slate. This substrate is used as a base as Coticule is a rather brittle material. Tiny hairline cracks may be visible along the edges of the stone. This is perfectly normal for such a brittle material and it has no influence at all on the sharpening properties. 

Differences in Coticule layers

The different Coticule layers that can be exploited are exposed to various environmental factors during their formation. This results in the hardness and composition of the Coticule seams differing from each other. A harder Coticule is more suitable for sharpening of woodworking tools. The likelihood of cutting into the Coticule is very small. 

A softer Coticule has the advantage of releasing its garnets very quickly, thus creating a grinding compound. This property is particularly appreciated by razor users. If you would like to learn more about the characteristics of the different Coticule-layers we advice you read following article written by Henk Bos.


Sharpening of chisels and gouges

Coticule Slipstone: for round chisels and gouges. This is a rectangular whetstone with a Coticule top layer glued onto a substrate of unusable black slate. The length is approximately 75 mm and is available in three different curve diameters: < 7 mm, between 7 - 12 mm of > 12 mm.

Coticule Multiform: for round and V-shaped chisels and gouges. The slipstone is wholly made of Coticule and has 1 round and 1 sloping side. Available in 4 different combinations. A curved side of diameter < 5 mm or > 5 mm and length < 50 mm or > 50 mm. The angle of the V-shaped side is approximately 45°.

Belgian Blue Whetstone

Whetstones in different shapes

We produce a comprehensive range of BBW whetstones with the suitable profile for sharpening various cutting tools. The profile of the whetstones can easily be adapted to your wishes easily by making use of the softness of the stone.

Combination whetstones