Grit numbers explained
A whetstone's number is its grit: how fine its abrasive particles are. Lower numbers are coarser and remove steel quickly; higher numbers are finer and refine the edge left by the stone before. You move from coarse to fine, never the other way round.
| Band | Grit | What it does | Do you need it? |
|---|---|---|---|
| Coarse | #120–600 | Repairs chips, reshapes a broken tip, resets a very dull edge | Optional — rarely needed |
| Medium | #700–2000 | Does the actual sharpening and raises a burr | Essential — buy this first |
| Fine | #3000–8000 | Refines and polishes the edge for keenness and glide | Recommended second stone |
| Polishing | #10000+ | Mirror finish and a very refined edge | Optional — enthusiasts |
For a kitchen knife the finest stone you really need is around #6000. Beyond that, the edge becomes so polished that it can feel slick on tomato skins and onions; a slightly toothier edge from a #3000–6000 stone often cuts food better. Polishing stones are for enthusiasts who enjoy the process.
Why grit numbers don't match between brands
There is no single grit scale. Most Japanese whetstone makers grade to the Japanese JIS system; sandpaper and many Western abrasives use other standards; and the particle size is only part of how a stone behaves — the binder, the hardness and the type of abrasive all change how fast it cuts and what finish it leaves. Two "#1000" stones from different makers can feel noticeably different.
In practice: compare numbers within one maker's range, and treat numbers across brands as approximate. A stone labelled in microns (µm) is giving you particle size directly — smaller is finer.
Types of sharpening stone
| Type | How it's used | Strengths | Watch out for |
|---|---|---|---|
| Soaking water stone | Soak in water until bubbles stop (typically 5–15 min), keep the surface wet while sharpening | Traditional feel, builds a cutting slurry, usually inexpensive | Softer ones wear hollow faster; must dry fully before storing |
| Splash-and-go stone | Wet the surface only; many makers say not to soak | Ready in seconds, often harder and slower to dish | Some crack if left in water — follow the maker's instructions |
| Combination stone | Two grits bonded back to back, e.g. #1000/#6000 | Sharpening and finishing in one inexpensive block | Each side is thinner than a full stone; the two sides may need different wetting |
| Diamond plate | Diamond particles on a steel plate, used with water | Fast, stays flat, cuts very hard steels; ideal for flattening other stones | Coarse plates leave deep scratches; fine plates are expensive |
| Natural stone (tennen toishi) | Quarried stone, mostly used for finishing | Distinctive finish prized by enthusiasts and traditional sharpeners | Inconsistent from stone to stone, expensive, not needed to get a sharp knife |
| Oil stone (Arkansas, India) | Used with honing oil rather than water | Long-lasting and common in Western woodworking | Generally slow on hard Japanese steel; never put oil on a water stone |
For Japanese kitchen knives, synthetic water stones — soaking or splash-and-go — are the standard choice. A diamond plate earns its place as a flattener. Natural stones and oil stones are optional detours, not requirements.
Soaking vs splash-and-go
Soaking stones are porous; they are soaked until air bubbles stop rising, usually 5–15 minutes, so they stay wet through a session. Splash-and-go stones are denser; you wet the surface and start, and several makers say not to soak them at all. Many fine finishing stones should not be left in water either, and some can crack if they are.
Neither type sharpens better. Splash-and-go is more convenient for quick touch-ups; soaking stones are often cheaper. The rule that matters is the one on the box: wet the stone the way its maker says, and let it dry completely before you put it away.
What to buy: three simple setups
| Setup | Stones | Who it suits |
|---|---|---|
| Minimal | #1000/#6000 combination + flattening plate | Most home cooks with one or two knives |
| Standard | Separate #1000 and #4000–6000 stones + flattening plate | Regular sharpening, several knives |
| With repairs | Standard set + a #220–400 coarse stone | Fixing chips and broken tips, restoring old knives |
Well-known Japanese makers of synthetic stones include King, Naniwa, Shapton and Suehiro, and each offers stones across the grit range. We have not run our own side-by-side tests of these brands, so we don't rank them here; within a reputable maker's range, choosing the right grit and size matters far more than the brand.
Size, hardness and a stable base
- Size: a stone about 180–210 mm long and 60 mm or more wide gives you room for long, even strokes and makes a consistent angle much easier. Small "pocket" stones are for tools, not kitchen knives.
- Hardness: softer stones release abrasive quickly and cut fast with plenty of slurry, but they wear hollow sooner. Harder stones stay flat longer and feel more precise but can feel slower.
- Base: the stone must not move. Use a rubber stone holder, a bridge over the sink, or a damp towel on a solid counter.
Matching the stone to your steel
- Carbon steels (Shirogami, Aogami) sharpen quickly and easily on almost any water stone.
- Common stainless (VG10, Ginsan) sharpens well on ordinary synthetic stones.
- Powder steels (SG2 / R2 and similar) are very wear-resistant, so they take longer on soft stones. Harder synthetic stones or a diamond plate speed this up.
Compare the steels themselves in the Japanese knife steel chart.
Looking after a stone
- Flatten it regularly. Every stone wears into a shallow dish, which then rounds your edge. Flatten it every few sessions with a flattening plate or coarse diamond plate — see how to flatten a whetstone.
- Rinse and dry. Rinse off the slurry and let the stone dry fully at room temperature before storing it; never put a wet stone in a closed box.
- Keep it from freezing. A soaked stone left somewhere below freezing can crack.
- Keep grits apart. Rinse your knife and hands between stones so coarse grit doesn't scratch a fine stone.
What to skip
- Pull-through sharpeners: they remove metal unevenly and can chip hard Japanese edges.
- Very small stones: too short for a kitchen knife and hard to keep the angle on.
- Extreme grits first: a #10000 polishing stone or a #120 coarse stone is not a good first purchase.
- Oil on water stones: it clogs them permanently.
The bottom line
One #1000 stone and a way to keep it flat will keep a Japanese knife sharp. Add a #3000–6000 stone to refine the edge, and a coarse stone only when something needs repairing.
Ready to use it? Follow how to sharpen a Japanese knife on a whetstone, and read honing vs sharpening and stropping for keeping the edge between sessions.
Frequently asked questions
What grit whetstone should I buy first?
A medium stone around #1000. It does the actual sharpening, and with it alone you can keep a Japanese knife genuinely sharp. The easiest start is a #1000/#6000 combination stone, which adds a finishing side, plus something to flatten it. Coarse stones (#220–400) are only for chips and very dull edges.
What do the numbers on a whetstone mean?
The number is the grit: how fine the abrasive particles are. Lower numbers are coarser and remove metal quickly; higher numbers are finer and refine the edge. Most Japanese makers grade to the Japanese JIS scale, which is not the same as sandpaper grades, and two stones with the same number from different makers can feel quite different, so treat the numbers as a guide rather than an exact measurement.
Do you soak a whetstone?
It depends on the stone. Traditional soaking stones are soaked until the bubbles stop, usually 5–15 minutes. Splash-and-go stones only need their surface wetted, and several makers warn against soaking them or leaving them in water. Many fine finishing stones should not be left soaking either. Check the maker's instructions for your stone.
Is a #1000/#6000 combination stone good enough?
For most home cooks, yes. The #1000 side sharpens and the #6000 side refines the edge to a keen, smooth finish that suits Japanese kitchen knives. You would only add a coarse stone for repairing chips, or a separate higher-quality stone later if you sharpen often.
What is the best whetstone for beginners?
One that is easy to keep flat and forgiving to use: a medium #1000 stone (or a #1000/#6000 combination) of full size, around 180–210 mm long and 60 mm or more wide, on a stable base. Add a flattening plate or a coarse diamond plate. Buying a large stone matters more than buying an expensive one — small stones make it hard to hold a consistent angle.
Are diamond stones good for Japanese knives?
Diamond plates are excellent for flattening your water stones and for sharpening very hard, wear-resistant steels quickly. For everyday sharpening, many people prefer water stones because coarse diamond plates leave deep scratches and can be aggressive on a thin edge. A fine diamond plate works well; just use a light touch.
How long does a whetstone last?
Used by one home cook, a good medium stone usually lasts for years. Softer stones wear faster than harder ones, and coarse stones wear faster than fine ones. It will wear unevenly unless you flatten it regularly, which also extends its useful life.
Can I use oil on a Japanese water stone?
No. Water stones are made to be used with water; oil clogs the surface and stops them cutting properly, and it cannot really be removed. Oil stones such as Arkansas stones are a separate type that is used with oil from the start.
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