Belgian Blue

Belgian Blue

Hand-Made Natural Whetstone

For final finishing and a 'shaving sharp' edge

In our opinion this is best all-round finishing stone in the world. It is used with slurry as a fine whetstone (approx. #4000 grit). However, with the slurry washed off and a lighter pressure it also works as a strop (approx. #12000 grit) giving a ‘shaving sharp’ edge.

Hand-made in Belgium at a small, family-owned mine called Ardennes Coticule, the Belgian Blue gained fame in the world of cut throat razors. This full size version can get a kitchen knife sharper than any other method we’ve used. And we’ve used a lot.



in the box

• Full-size Belgian Blue natural whetstone 209x73x18mm
• Belgian Blue slurry stone 73x18x10mm
• Solid Beech and Birch-ply storage box
• 100% recycled rubber non-slip mat
• Birch ply angle guide – 15º & 20º


Belgian Blue whetstones are created from a 480 million year old sedimentary rock only found in one location in the world. A tonne of this rock is required to make each stone.

These stones have been produced in Lierneux since 1625. Then with the advent of synthetic whetstones, production of natural stones declined. In 1982 the mine closed. By the 90's, however, there was an understanding that Belgian natural stones actually outperform synthetic ones. Maurice Celis and his son Rob re-opened the mine. Ardennes Coticule was formed.

Ardennes Coticule Mine

two stones in one

The Belgian Blue consists of around 25% garnet crystals bonded with mica. The garnets are dodecahedron in shape, have a diameter of 5 to 15 microns. In a slurry they penetrate 1 to 3 microns into the metal to be sharpened, creating a #4000 grit edge. Their ideal geometric shape (obtuse angles polish the metal) and the large numbers of these garnets means the blade is sharpened very quickly and extremely finely. No other whetstone can match it.

With the slurry washed off, the embedded garnets stick up out of the surface by around half their diameter, or less. The shallower scratches produced by this finer surface are equivalent to approx. #12000 grit and replace the need for a leather strop.

a fine edge

For knives already sharpened with a medium stone, use the Belgian Blue to quickly create a fine edge of around #4000 grit. This is our recommended ideal edge – it is a little more durable than a #12000 edge due to having ‘microserrations’. TOG kitchen knives are supplied with a #3000 edge.

There is no need to soak the Belgian Blue. Splash some water on the surface then rub the little slurry stone in circles to create a paste / slurry. This speeds up the process. The slurry contains garnets which do the sharpening. Do not use a honing rod afterwards.


To polish or “strop” your knife and produce the sharpest edge possible, wash the slurry off under the tap. Continue to sharpen on the clean Belgian Blue, but use lighter pressure to avoid creating a slurry. This will refine the edge further and produce a ‘shaving sharp’ edge.

Hold the knife at a couple of degrees greater angle than before to ensure you’re working the very furthest point of the cutting edge. Use 10 to 15 strokes on each side of the blade. The edge produced is perfect for sushi or wherever you wish to get the cleanest cut possible.




Caring for your stone

The Belgian Blue should be dried before returning it to its wooden box for storage. As soon as it looks dry, it is dry. It is non-porous. You can clean it before drying it, or keep the slurry and dry it with the slurry on it. The slurry stone can also be used for cleaning up the surface of the stone. The Belgian Blue can also be flattened with a diamond plate if it starts becoming dished.

After Care

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