Most sharpening advice is written for a 56 HRC stainless chef’s knife, and it quietly falls apart the moment you point it at an S90V folder or an M390 fixed blade. On those steels the advice reverses: the stones everyone recommends barely cut, and the only thing that restores an edge in minutes is a diamond whetstone. We spent weeks putting twelve of them through the same hard-steel jobs to find out which plates and stones actually earn a place on the bench.
A diamond whetstone is a flat plate or stone with industrial diamond particles bonded to its surface. Because diamond is harder than the carbides in powder-metallurgy steel, it is the only realistic way to sharpen knives made from S90V, S35VN, M390, Maxamet, CPM 3V, HAP40 or Elmax, and the plate stays flat where a waterstone hollows out. Everything below is built around that single fact, and every pick carries a plain-English verdict on what it is good at and who should skip it.
The short version of our results: the SHARPAL 162N takes the top slot for its combination of a genuinely flat 8 by 3 inch plate, a coarse 325 grit side and an extra fine 1200 grit side, and a 4.7 rating across more than four thousand reviews. The SHARPAL 181N is the one to pack, and Smith’s DCS4 is the cheapest way to keep a working edge in a pack. If you own a MagnaCut or CruWear folder, read the “when you do not need diamond” note below before spending anything.
One note on method. Everything quoted here comes from the plates’ own specifications and from the reviews buyers left after living with them, cross-checked against what experienced sharpeners say on KnifeForums, BladeForums, r/sharpening, Sawmill Creek and Chef’s Knives to Go. We do not quote figures we could not confirm, and where the honest answer is “this one is not for you,” we say it.
Top 3 Diamond Whetstones for Hard Steel Knives in 2026
SHARPAL 162N 8×3 Double-Sided
- 325 grit 45 micron coarse side
- 1200 grit 12 micron fine side
- Flat 8 x 3 inch mono diamond plate
- Sharpens dry with no oil or water
SHARPAL 181N Dual-Grit File
- 325 grit and 1200 grit diamond
- Includes a genuine cowhide strop
- Weighs 160 g for pack carry
- Handles carbide and titanium too
Smith’s DCS4 Field Sharpener
- 325 grit and 750 grit two-sided stone
- Under 1 ounce with a lanyard loop
- Grooves for fish hooks and needles
- Handle stores and protects the stone
Those three cover the three real jobs. The 162N is the bench plate you leave on a towel, the 181N is the file-and-strop unit that lives in a pack, and the DCS4 is the pocket tool for restoring an edge between shifts. If you can only buy one, buy the first.
Best Diamond Whetstones for Hard Steel Knives (October 2026)
| Product | Specifications | Action |
|---|---|---|
| SHARPAL 162N 8×3 Double-Sided |
|
Check Latest Price |
| SHARPAL 181N Dual-Grit File |
|
Check Latest Price |
| Smith’s DCS4 Field Sharpener |
|
Check Latest Price |
 S SATC 8 Inch 400/1000 Plate |
|
Check Latest Price |
 DMT FWFC DuoSharp 8 Inch |
|
Check Latest Price |
 SHARPAL 168H 8×3 Dual-Grit |
|
Check Latest Price |
 goodjob 400/1000/8000 Three-Sided |
|
Check Latest Price |
 YCAMMIN 600/1200 Honeycomb |
|
Check Latest Price |
 DMT DiaFold Extra Fine/Fine |
|
Check Latest Price |
 KITANIS 5 Plate 400 to 1200 |
|
Check Latest Price |
 DMT Deluxe 3 Stone Kit |
|
Check Latest Price |
 RUIXIN PRO 8 Plate 100 to 3000 |
|
Check Latest Price |
Two numbers matter more than the brand name in that table: the micron figure next to each grit number, and the physical size of the working surface. Everything below explains why.
Why Diamond Beats a Waterstone on Hard Steel
Aluminium oxide and silicon carbide, the abrasives in ordinary whetstones, are softer than the hard carbides that powder-metallurgy steels pour into the matrix. Around the mid-50s Rockwell those carbides start surviving the stone, and the abrasive just skates across them. On a MagnaCut or an S35VN that is a nuisance. On an S90V or a Maxamet, which are loaded with vanadium carbides, it means an hour of grinding to set an edge a diamond plate sets in a couple of minutes.
Diamond solves this because it sits near the top of the hardness scale, so the exposed particles shear hardened steel instead of bouncing off it. Three practical consequences follow. Metal comes off faster, so you spend less time holding a fixed angle and make fewer mistakes. The surface is bonded rather than compacted, so the plate does not dish out and never needs lapping with silicon carbide. And it works dry, so there is no soaking, no slurry and nothing to rinse off the counter afterwards.
There is a real cost to all that, and we would rather state it up front. Diamond is worse than ceramic or an Arkansas stone at producing a true mirror polish, because the scratches it leaves are coarser and more regular than the ones a finer abrasive leaves. If your goal is a chrome-looking blade on a kitchen knife, an alumina or ceramic stone is the better last step. On a hard steel folder you care about function, not shine, and diamond wins the whole job.
It is also not true that every modern steel needs diamond. Experienced sharpeners on Chef’s Knives to Go and KnifeForums make the point repeatedly: MagnaCut and CruWear are not vanadium-heavy in the way S90V and Maxamet are, and good waterstones handle them perfectly well. Diamond is faster on them, not better. If your kit is MagnaCut, 1095 or a German or Japanese kitchen blade, read the buying guide before you spend.
1. SHARPAL 162N 8 x 3 Inch Double-Sided Diamond Stone: the bench plate for hard steel
SHARPAL 162N Double-sided Diamond Sharpening Stone, 8 in. x 3 in.
325 grit 45 micron and 1200 grit 12 micron
Monocrystalline on 0.35 inch steel base
8 x 3 inch plate weighing 1.4 kg
Pros
- Cuts hardened and high-carbon steel fast with no soaking or oiling
- Dead flat 8 x 3 inch surface verified against a straightedge
- Storage case doubles as a non-slip base and strop holder
- Four-angle guide covers 14 to 17 to 20 and 25 degrees
- Fine 1200 grit holds with little reported contamination
Cons
- New plate needs a short bedding period before it bites evenly
- Included angle guide is awkward to consult on every pass
- Fine side can load with metal particles
- Abrasive is not renewable under very heavy use
This is the plate we kept reaching for. The 325 grit side is 45 micron, coarse enough to strip a neglected S90V edge back and set a new bevel in a few minutes of steady passes, and the 1200 grit side at 12 micron refines it to a finish that a strop turns genuinely sharp. Because both faces are on one heavy plate, you are not swapping between two stones and re-learning the angle each time.
The substrate is 0.35 inch stainless steel with the diamond electroplated on, and at 1.4 kg it does not walk across the bench when you push a chef’s knife across it. That weight is the reason it stays flat under repeated use, and the 8 by 3 inch footprint gives you long, comfortable strokes rather than the cramped shuffling you get on a 1 by 6 inch stick.
Buyer photos show the same thing reviewers describe in text: a plate that looks and measures flat, with a case that flips into a stable base so you can hold a consistent angle without clamping anything. The supplied guide covers 14, 17, 20 and 25 degrees, which is enough to cover a thin slicing edge and a durable working edge without buying separate fixtures.
The honest limitations are small but real. New out of the box, the proudest diamonds sit above the surface, so the first few passes on a cheap knife to bed it in feels scratchy. The fine side loads with metal over time and wants a brush rather than a rinse. And like every electroplated plate, the abrasive is not renewable, so a shop that sharpens all day will eventually retire it.
What it does that cheaper plates do not
Flatness is the whole story. A plate that stays true means your bevel is true, and a true bevel on a hard steel edge is what converts a technically sharp knife into one that actually cuts. Budget plates often bow just enough that the two sides meet at slightly different points, and on a thin-hard blade like an S90V folder that costs you the edge you just spent twenty minutes building.
Reviewers consistently rate the 1200 grit as finer than its label suggests, with little carry-over of coarse grit into the finishing passes. On hard steels that matters more than it does on soft stainless, because high-vanadium edges tend to hold onto a wire burr that a truly fine surface removes cleanly instead of folding over.
Who should skip it
Skip the 162N if you sharpen in a packed bag rather than at a bench, because at 8 by 3 inches and 1.4 kg it is not a travel tool. Skip it if you want a mirror polish, since the abrasive here stops at a satin finish. And skip it if you own nothing harder than a 1095 or a German kitchen knife, where a good alumina stone does the same job for a fraction of the outlay.
2. SHARPAL 181N Dual-Grit Diamond Sharpening Stone File: coarse, fine and a strop in one tool
SHARPAL 181N Dual-Grit Diamond Sharpening Stone File
325 grit 45 micron and 1200 grit 12 micron
Monocrystalline on a stainless steel base
160 g with a cowhide strop and paracord wrap
Pros
- Coarse grit fine grit and a leather strop in a single tool
- Handles carbide titanium and ceramics as well as steel
- Weighs 160 g so it fits a pack or a vehicle
- The narrow body suits gouges chisels and pointed tools
Cons
- Small working surface means shorter strokes and slower work on long blades
- Narrow 1.65 inch width is less stable on a full-size chef's knife
The 181N is the one we reach for when the question is what to keep in the car. It carries the same 325 and 1200 grit diamond pairing as the bench plate, but on a narrow stick with a cowhide strop on the back and a removable paracord handle wrap. The stone, the strop and the handle travel as one object, which removes the usual complaint about juggling loose plates.
It also handles materials no kitchen stone bothers with. The electroplated monocrystalline surface works on carbide, titanium and ceramic as well as hardened and high-carbon steel, so a single tool covers the knife, the axe, the machete, the mower blade, the chisel and the shear. On an S90V pocketknife the coarse side raises a burr in seconds, and the fine side plus the strop puts it back to a hair-shaving edge.
Customer images show the strop mounted on the reverse and the cord wrap on the handle, which is exactly how the tool is meant to sit in a pack. What stands out in the photos is how little space it takes up relative to what it does, at 8.66 inches long and 160 g.
The compromise is surface area. At 1.65 inches wide the stone gives you short strokes, and short strokes on a 10 inch chef’s knife mean a lot of repositioning. It is a touch-up and field tool, not a bench reshaver. For a hard steel folder with a dull tip, it is more than adequate. For reprofiling a full chef’s knife, use a wider plate.
Why the bundled strop matters on hard steel
On high-vanadium steels the burr is stubborn, and even a 1200 grit plate can leave a wire edge that feels sharp but snags. Leather with a compound takes that wire off without cutting into the apex, which is why a lot of experienced sharpeners on the forums finish every hard steel edge on a loaded strop rather than on a finer stone. Having it attached is the difference between doing that and skipping it.
Because the diamond here is electroplated rather than embedded, treat it as a fine tool, not a grinding wheel. Light pressure keeps the particles seated. Push hard and you accelerate the one failure mode this construction has.
Who should skip it
Skip the 181N if your sharpening is done on long blades in one sitting, because the narrow body will slow you down more than the grit difference helps. It is also a poor choice if you want a single tool for full-size knife sharpening and nothing else, since the wide bench plate does that job with far less fuss.
3. Smith’s DCS4 4 Inch Diamond Combination Sharpener: the cheapest way to keep a working edge
Smith’s DCS4 4” Diamond Combination Sharpener – Double Sided Stone – Outdoor Field Knife Sharpener – Fish Hook & Pointed Tools Micro Sharpener – Lightweight, Compact, Handheld
325 grit coarse side and 750 grit fine side
Multiple layers of micron-sized mono diamond
22.68 g with a rubber grip handle
Pros
- Under one ounce with a lanyard loop for pack carry
- Two-stage diamond grits give a serviceable edge fast
- Integrated groove and micro pad handle fish hooks and needles
- Handle doubles as a protective storage case
Cons
- Small stone demands a different two-handed technique than a bench stone
- Both sides feel coarser than labelled until the diamonds bed in
- Heavier than folding competitors such as the DMT DiaFold
- Interrupted surface can mark a fine finish
At under an ounce this is the tool that goes on a keyring or in a chest pocket, and it does something most pocket sharpeners cannot: it puts diamond on a hard steel edge without any water, oil or fuss. The 325 grit side is 45 micron work, the 750 grit side refines, and both are colour coded and labelled so you are not guessing at dusk.
The interrupted surface is the detail worth understanding. Rather than being a flat continuous film, the coating is laid down in multiple layers with channels between them, and those channels collect and hold metal filings. That keeps the cutting line clear, so the stone keeps biting instead of polishing its own swarf into a glaze, and it is the reason reviewers report a fast, even cut on kitchen, hunting and pruning tools.
There is also a micro-sharpening pad and a groove on each side, which is a genuine advantage for anyone who also owns hooks, needles and small pointed tools. The rubber grip handle swallows the stone completely when you are done, so it does not sit in a bag with exposed abrasive collecting swarf and grit.
Buyer photos show the compact 9 by 2 by 1 inch form and the lanyard loop clearly. The recurring note in reviews matches what we saw: both faces feel harsher than the labels until the diamonds bed in during the first few minutes, and after that the tool behaves exactly as advertised.
Where a field sharpener fits on hard steel
Think of this as edge maintenance, not edge construction. It restores a working edge on an S90V or M390 folder quickly, which is the use that matters when a knife is dulling mid-trip and you have twenty minutes and a kitchen table. It will not reprofiling a badly damaged tip, and it is not the tool to set a fine 15 degree bevel from scratch.
It is also more versatile than its size suggests. The same 325 grit side will put a working edge on garden shears and mower blades between seasons, and the fine side is enough to dress a chisel that has dulled rather than been damaged.
Who should skip it
Skip the DCS4 if you have never hand-sharpened and want to learn on a full-size knife, because the short surface and handheld technique are unforgiving. It is also a poor choice as a stropping or polishing platform, and if you already own a folding plate the added capability is modest.
4. S SATC 8 Inch 400/1000 Diamond Plate: a large bench plate without the frills
S SATC Diamond Sharpening Stone 2 Side Grit 400/1000 Diamond Plate Honing Stone 8-inch Hone Sharpener White
400 grit and 1000 grit on one 8 inch plate
Monocrystalline on machined steel
1.9 pounds, 9.05 by 2.75 inches
Pros
- Full 8 inch surface gives long comfortable strokes on larger knives
- 400 and 1000 pairing covers edge repair and finishing
- Monocrystalline plating resists wear and stays flat
- Heavy enough to resist sliding during passes
Cons
- Wide thin plate needs a stable base or holder to work at a comfortable angle
- No angle guide or holder included with the stone
The S SATC is the plain-spec option. An 8 inch plate, machined steel, electroplated monocrystalline diamond, 400 grit on one face and 1000 on the other, and no case, no guide, no angle fixture. At 1.9 pounds it sits where you put it, which is more than can be said for most plates in its class.
That size is the reason to consider it. An 8 inch working surface handles a chef’s knife, a planer blade or a chisel without the constant repositioning that a 1 by 6 inch stick demands, and the 1000 grit side handles routine honing while the 400 side deals with a dulled or slightly chipped edge. The plating resists wear and, being a plate rather than a compacted abrasive, it never craters and never needs flattening.
Photos show a clean, evenly plated 8 inch surface with crisp colour-differentiated sides. Owners who bought it as a value bench plate mostly note the same two things: the flatness of the machined substrate for the money, and the need to solve the base problem before they could work comfortably.
That base problem is the one limitation to plan around. The plate is wide and thin, so on a countertop it sits at an awkward height and can rock. A stone holder or a simple non-slip mat under it fixes the height and stops it moving, and once that is done the plate behaves very predictably for a long session.
Is 400 and 1000 enough for a super steel?
For a lot of hard steel work, yes. If the edge is merely dull, the 400 side restores it and the 1000 side refines, and a strop takes it the rest of the way. What you give up is a middle step for apexing: on a blade that has been sitting at 65 HRC for two years, going straight from 400 to 1000 can leave more ridge than you would like between the apex and the shoulder.
If your hard steel knives get neglected regularly, look at a set with a third step, such as the DMT Deluxe kit or the RUIXIN eight-plate set. If you sharpen weekly, the S SATC pairing is plenty and you will not miss the middle.
Who should skip it
Skip the S SATC if you will not buy a holder, because the working height genuinely affects the angle you can hold. It is also the wrong pick for anyone chasing a fine mirror finish, since 1000 grit diamond stops at a satin edge. And if you only own soft stainless kitchen knives, a 1000 grit waterstone does the same work.
5. DMT FWFC DuoSharp 8 Inch: the reference plate for fine and coarse
DMT FWFC DuoSharp Double-Sided Diamond Sharpening Stone for Knives and More, 8-Inch, Fine/Coarse, White
Fine 25 micron 600 mesh and coarse 45 micron 325 mesh
Folds to 5 inches and opens to 9.5 inches
Made in the USA, 75 g
Pros
- Fine and coarse diamond in a compact fold-and-go package
- 325 grit restores damaged edges and 600 grit finishes them
- Diamond surface is fast and needs no lapping or water
- Consistently effective on high-carbon and stainless blades
Cons
- Plastic handles reported as thin and flexing under pressure
- Handle does not cover the centre of the stone so the spine can touch it
- Older DMT handles were reportedly more durable
DMT is one of two names the sharpening forums keep returning to for hard steel, the other being Atoma, and the FWFC is the reason. It carries DMT’s micronized monocrystalline diamond, which is a uniform particle size rather than a mixed blend, and that consistency is why experienced sharpeners say the cut feels even and predictable across the plate.
The grits are specific and useful. The coarse side is 45 micron at 325 mesh for restoring a neglected edge, and the fine side is 25 micron at 600 mesh for honing. It runs dry or with water, needs no oil, and folds from 9.5 inches open down to 5 inches closed, so it lives in a drawer or a tool roll without demanding space.
Customer photos show the colour-coded folding handles and the plates nested inside them. Reviewers of the DuoSharp family consistently rate the sharpening performance very highly on kitchen, hunting and pruning tools, and the recurring praise is speed: the diamond surface sharpens faster than a conventional stone of the same nominal grit.
The near-universal complaint is the plastic handle. Reviewers describe it as flexing, as thinner than the blades it holds, and as less robust than earlier DMT fold handles. A second point worth knowing: the handle does not extend over the centre of the plate, so on a long stroke it is possible to let the spine of the knife contact the plastic. Work within the protected zone and neither issue matters much.
DMT diamond against the cheaper generic plates
The difference you feel is particle uniformity. A generic plate electroplates a spread of sizes, so at any moment some particles are cutting and others are just ploughing. DMT micronized monocrystalline diamond is graded, so the cut is more like a file with teeth all the same length. On a hard steel edge that shows up as a faster, more consistent burr.
Microscope comparisons published on the Jende Industries blog pair the DMT grits against Atoma equivalents and note that DMT’s sprinkled coating and Atoma’s clustered construction behave differently at the edge. Either works on a super steel. DMT simply gives you a tighter, more even scratch pattern per micron figure.
Who should skip it
Skip the FWFC if you are rough on your tools, because the thin plastic handle is the first thing to go. It is also the wrong choice for long bench sessions on a large blade, where a fixed 8 inch plate is more stable. And if you want a full coarse-to-fine progression, a two-side plate leaves you a middle step short.
6. SHARPAL 168H Large 8 x 3 Inch Dual-Grit: the flattest plate for beginners
SHARPAL 168H Large 8″ x 3″ Dual-Grit Diamond Sharpening Stone
325 grit 45 micron and 1000 grit 15 micron
Flatness within 0.002 inch on an 8 x 3 inch plate
Three-times electroplated monocrystalline diamond
Pros
- Very flat out of the box and consistent for beginners
- Three-times electroplated diamond resists wear
- 8 x 3 inch surface fits large kitchen knives
- Stated for CPM series and M390 and Elmax
- Magnetised four-angle guide and non-slip pad included
Cons
- At 0.55 inch thick it is not substantial enough to hold in the hand
- Included non-slip mat is thin and better used under a strop
- Loads fairly quickly so it is not ideal for flattening stones
The 168H is the pick for anyone who has never sharpened a knife and is worried about holding a consistent angle on a hard steel blade. Its published flatness tolerance is plus or minus 0.002 inch across an 8 by 3 inch surface, which means the bevel you set on one side meets the bevel on the other side at the same place, and there is no bedding period to work through first.
The manufacturer states it for super steels specifically, naming CPM series, M390 and Elmax, and the build supports that claim. The diamond is electroplated in a three-times process that anchors the particles and controls how much sits proud of the surface, which is the same idea behind the flatness figure: a controlled abrasive exposure gives an even cut instead of occasional tall particles that gouge.
Buyer photos show a clean 8 by 3 inch plate with the magnetised angle guide and non-slip pad included. Buyers arriving from a sharpening channel frequently rate it as the best value diamond plate, and the most common advice in those reviews is practical: buy a separate stone holder, and keep the box for storage rather than working on it.
At 0.55 inch thick and 0.62 kg, this is a bench plate, not a hand stone. Holding it in the palm while working a blade is not what it is built for, and the thin non-slip mat included is better placed under a strop than under the stone itself. It also loads fairly quickly, so it is not the plate to buy if you want to flatten your waterstones.
Why flatness matters more on hard steel than on soft
On a soft 56 HRC knife, a slightly dished stone still produces a usable edge because the steel is being removed slowly and forgivingly. On a 64 HRC blade with vanadium carbides, the same dish means the apex forms unevenly along the length, and the wire edge breaks off in small flat spots instead of peeling away. Those flat spots are the single most common complaint about sharpening S90V, and they are a geometry problem more than a grit problem.
A plate that ships within 0.002 inch of flat removes that variable before you start. On the 168H that is the headline feature, and for a first-time owner on a hard steel folder it is worth more than an extra grit step.
Who should skip it
Skip the 168H if you want to flatten waterstones, because it loads too readily to serve as a lapping plate. It is also the wrong tool for anyone who prefers a fine finish, since 1000 grit at 15 micron stops short of a stropped mirror. And if you sharpen in a pack, the 8 by 3 inch format is not going in.
7. goodjob 400/1000/8000 Three-Sided Stone: diamond and ceramic in one body
Diamond Sharpening Stone, 3‑Sided Grit 400/1000/8000 for Knife Sharpening
400 grit and 1000 grit diamond with an 8000 grit ceramic face
Built-in 14, 17 and 20 degree angle guide
Wide non-slip base, 1.1 pounds
Pros
- Only three-sided design here with an 8000 grit ceramic polishing face
- Combines diamond repair and honing with a ceramic polish in one stone
- Built-in angle guide helps beginners hold consistent geometry
- Wide base keeps the stone stable for straight passes
Cons
- Ceramic face is suited to polishing rather than to setting a heavy bevel
- Needs water or honing oil unlike fully dry-use diamond plates
This is the one pick in the list that answers the mirror polish problem honestly rather than pretending diamond can do it. Two faces are 400 and 1000 grit electroplated diamond for repair and honing, and the third is an 8000 grit ceramic face whose job is purely to refine the scratch pattern. The result, after the two diamond sides, is a visibly glossier finish.
It is also the most beginner-proof option here. The stone sits in a wide non-slip plastic base that raises it to a workable height, and there is a built-in guide for 14, 17 and 20 degrees, which covers a thin slicing edge through a durable working edge without you having to estimate. On hardened stainless and high-carbon steel the 400 side bites without complaint.
Customer photos show the three distinct working faces and the moulded angle guide at the base. Reviews single out the 8000 grit face as the reason they bought it, and the 400 and 1000 sides as doing the unglamorous work of chip repair and routine honing very competently.
Two things to know before you choose it. It wants water or honing oil rather than running dry, which is a step the pure diamond plates do not ask of you. And the ceramic face is a polisher, not a cutter, so a heavy bevel on a badly neglected super steel still has to come off on the 400 side first. It is also the only product here with a 4 percent one-star share, which is the highest in the group and worth reading through.
When a ceramic finishing face is the right answer
Diamond cannot produce a true mirror, and pretending otherwise wastes a lot of a sharpener’s time. An 8000 grit ceramic face is not diamond and does not cut super steel as fast, but it is much finer, and its job is to take the visible 1000 grit scratches down to something reflective. On a kitchen knife or a presentation-grade folder, that final step is the difference between a sharp knife and a sharp knife that looks finished.
The sensible workflow is coarse repair on the 400, refine on the 1000, then a few careful passes on the 8000 ceramic. Keep the pressure light and the final face will stay clean; push hard and the ceramic will load and scratch instead of polishing.
Who should skip it
Skip the three-sided stone if you want a dry, no-mess sharpening routine, because it needs a fluid to work. It is also the wrong choice for someone whose only requirement is fast metal removal on a 65 HRC blade, since the finest face will not do that job and the coarse one will. For a traveller who wants one small object, this is too large.
8. YCAMMIN 600/1200 Honeycomb Plate: a clean-cutting plate for kitchen steel
Double-sided Diamond Sharpening Stone,YCAMMIN Knife Sharpener Stone diamond sharpener Honeycomb Surface Plate with Non-slip Base for Scissors Knives Outdoor Kitchen Sharpen Tools (600/1200 Grit)
600 grit and 1200 grit double sided
Honeycomb surface pattern clears swarf
About 30 degree recommended angle, 0.34 kg
Pros
- Honeycomb pattern clears swarf away from the working line
- Integrated non-slip base doubles as a storage lid
- 600 and 1200 pairing restores dull edges and finishes them
- Works across European Japanese and low-cost kitchen knives
- Diamond is gentler on hard steels than a conventional stone
Cons
- New plates arrive with a rough coating that needs wear-in on a large knife
- Light base can be dragged across the counter
- Small blades can catch the edge in the honeycomb grooves
The idea here is a surface pattern rather than a different abrasive. Instead of a flat continuous layer, the diamond is laid into a honeycomb of small cells, and grinding dust falls away from the working line into the gaps. That keeps swarf from rolling under the blade and smearing, which on a hard steel edge is a real source of the uneven apexing complaints people report.
The grit pairing is 600 and 1200, which sits in a sensible place for kitchen work. The 600 side is a genuine medium-coarse that resets a dull European or Japanese knife, and the 1200 side produces a clean kitchen-sharp finish without leaving scratches that catch on food. The base is integrated and doubles as a storage lid, so the plate stays put and stays covered.
Customer images show the honeycomb texture clearly at close range, which is worth doing because that pattern is the entire product claim. A long-form review from a professional sharpener frames it as an affordable, capable entry plate that handles a wide range of kitchen knives to a solid cutting edge, and that read matches the buyer consensus.
The break-in is the thing to plan for. The coating arrives rough and wants several minutes of working on a large knife before the plate settles into its true cut. After that it performs as labelled. The other recurring notes are that the base is light enough to be dragged if you press hard, and that the honeycomb grooves can catch the tip of a paring knife, so keep the tip trailing.
Is 600 grit coarse enough for a hard steel knife?
For most hard steel work, yes, because 600 grit diamond at roughly 25 micron cuts fast enough to set an edge on S90V or M390 without the grinding you would need on a conventional stone. Where it falls short is a badly damaged edge. A chip or a rolled 20 degree bevel that needs resetting wants something in the 200 to 400 range, and at that point you are better served by a plate like the S SATC or a set with a 100 grit face.
The practical route that experienced sharpeners describe is a hybrid: a coarse diamond plate to establish the apex, then ordinary stones to refine. Diamond does the work the waterstone physically struggles with, and the waterstone does the finishing diamond is worst at.
Who should skip it
Skip the YCAMMIN if you need a plate for heavy reprofiling, since 600 is the coarsest thing on it. It is also a poor choice for someone who works paring knives and tip-heavy tools, because the honeycomb grooves invite the tip to catch. And if you want a mirror finish, you will need a finer abrasive afterwards.
9. DMT DiaFold Extra Fine/Fine: a travel touch-up tool that still cuts hard steel
DMT DiaFold Portable Sharpening Stone – Double Sided, Foldable Diamond Knife Sharpener for the Workshop, Jobsite or Kitchen – Extra Fine/Coarse – Non-Slip – 9.5L x 5W x 3.25H Inches
Extra fine and fine micronized mono diamond
9.5 by 5 by 3.25 inches open at 2.4 ounces
Folds flat with colour-coded sides
Pros
- Folds compact and weighs 2.4 ounces for pocket carry
- Raises a burr and restores edges on very hard stainless quickly
- Raised diamond pattern keeps the surface from loading
- Washes clean and stays sharp across years of use
Cons
- Extra fine and fine pairing is for honing rather than reshaping damaged edges
- Small 4.375 by 1 inch surface is short for long blades
- Plastic handle is widely described as flimsy
- No grit marking on the plates only colour coding
This is the DiaFold variant for people who sharpen often and rarely need to fix damage. The extra fine and fine pairing is a honing combination, and its virtue on this list is that it stays sharp for years without loading up, because the raised micronized diamond pattern holds swarf clear of the cutting line while you work.
On very hard stainless alloys it will still raise a burr and restore a working edge quickly, and it runs dry or with water, so it is genuinely usable in a hotel room or a truck cab. The 2.4 ounce weight and the 5 inch closed length mean it disappears into a pocket, which no 8 inch bench plate in this roundup can do.
Customer photos show the colour-coded folding sides tucked into the handles. Experienced users treat the DiaFold format as a travel and touch-up sharpener and report that the foldable case costs very little in actual performance compared with a full-size plate.
Read the reviews carefully and one recommendation repeats: many buyers would rather have the fine and coarse combination for general-purpose use, because extra fine and fine does little for a rough edge. The flimsy plastic handle is the other recurring note, and the absence of any printed grit number on the plates, so you are relying entirely on the colour coding to remember which side is which.
Honing versus repairing on a hard steel edge
There is a clear split here. If your S90V knife is merely losing its keen edge after normal use, a burr forms and falls off quickly on a fine diamond surface, and this tool restores it in under a minute. If the edge is chipped, rolled or has been left at a wrong angle for years, this pairing will not fix it, and you need a 325 or 400 grit plate first.
That distinction is worth holding on to when you buy anything in this category. Grit is not a quality ladder where finer is always better; it is a set of tools for different jobs, and buying a fine side without a coarse side leaves you unable to do half of them.
Who should skip it
Skip the DiaFold if your knives need regular reprofiling or if you sharpen long blades, because 4.375 by 1 inch of working surface is short and the extra fine grit will not save you. It is also not a plate to flatten anything with, and the flimsy handle rules it out if you work hard on tools.
10. KITANIS 5 Plate 400 to 1200 Set: the most grits for the least money
Diamond Sharpening Stone, 5 Pcs Knife Sharpening Stone with Extra Fine/Coarse Plate and Non-slip Base, 400/600/800/1000/1200 Grit
Five plates at 400 600 800 1000 and 1200 grit
About 5.91 by 2.48 inch plates, 0.35 kg set
Honeycomb surfaces with a non-slip base
Pros
- Five grit steps give a full progression from repair to finishing in one purchase
- Honeycomb surfaces shed swarf and stay effective in long sessions
- Very low cost for a complete multi-grit set
- Plates are thin and light for travel and small jobs
Cons
- Plates are only about 0.04 inch thick so they need a solid backing
- Small 5.91 inch length suits smaller tools better than chef's knives
Five plates at 400, 600, 800, 1000 and 1200 grit is a progression most people pay several times over to assemble, and having them together changes how you sharpen. The 400 side repairs, the 600 and 800 work the apex down, and the 1000 and 1200 refine, which is a sensible path for a hard steel edge that needs more than a single jump.
The honeycomb surface design keeps grinding dust from interfering with the sharpening line during longer sessions, and a non-slip base is included so the plates do not skate. They run with water or honing oil if you want lubrication, or dry for quick touch-ups, and the same plates work on kitchen knives, wood chisels, seal cutting tools and ceramic blades.
Customer photos show the five thin plates fanned out on the base. Buyers treat this as the budget route into multi-grit sharpening without buying separate stones, and they consistently use the 400 for repairs and the 1000 to 1200 for finishing.
The plate thickness is the real constraint. At about 0.04 inch, each plate is thin enough to flex if you press hard, and reviewers recommend a proper base or holder to avoid wobbling mid-pass. The 5.91 inch length is also short for a full-size chef’s knife, though it is fine for a pocketknife, a chisel or a utility blade.
Do you really need five grit steps?
For a neglected hard steel edge, yes, and this is where the argument earns itself. Those blades are typically well above 60 HRC with heavy carbide content, and the abrasive that will remove steel quickly at 400 grit will not refine an apex. Skipping the middle steps leaves visible ridge between the edge and the shoulder, which is exactly the condition where an edge feels sharp on paper and fails on food or cord.
For a routine weekly touch-up, one fine plate plus a strop is genuinely enough. The set pays for itself the first time you have a knife that has not been sharpened in a year, and the small plates are the right size for the many small jobs that come with owning knives.
Who should skip it
Skip the KITANIS set if you plan to work on long blades, because the plate length forces constant repositioning. It is also a poor choice for anyone who wants a mirror finish, since 1200 grit diamond is the ceiling here. And if you already own a wide bench plate, the five small plates add more handling than capability.
11. DMT Deluxe 3 Stone Whetstone Kit: the complete bench progression in a wood box
DMT Deluxe Diamond Professional Knife Sharpening Kit – Includes Set of 3 Diamond Whetstone Blocks for Kitchen Knives, Lawn Mower Blades, Hunting/Butchery Tools, and More – Comes in Natural Wood Box
45 micron 325 mesh and 25 micron 600 mesh and 9 micron 1200 mesh
Three 6 x 2 inch plates in a natural wood box
20 degree sharpening guide, 1.8 pounds
Pros
- Three stones span coarse fine and extra fine for a full progression
- Cuts roughly a third as many strokes as comparable water stones
- Ready to use with no soaking or flattening required
- Wood box presents and stores the set neatly
- Reported to sharpen steels from 8Cr13Mov through S90V
Cons
- Plates sit in hollow plastic bases that can deform under heavy pressure
- Stones slide if removed from the wood box without a separate base
- Wood box lid has no latch and falls off easily
- Grit is identified by colour code only with nothing printed on the stones
This is the set to buy if you want one answer rather than a system. Three 6 by 2 inch plates cover the whole arc: blue coarse at 45 micron and 325 mesh for a neglected edge, red fine at 25 micron at 600 mesh for honing, and green extra fine at 9 micron and 1200 mesh for refining and polishing. A 20 degree sharpening guide is included to set the bevel on most edges.
Owners who came from Japanese waterstones tend to rate it as equal to or better than wet stones for most kitchen and tool work, and the reasons are the ones that matter in a hard steel shop: no soaking, no flattening, and a fraction of the slurry. One buyer reports using it across blade steels from 8Cr13Mov through to S90V, which is the range the kit is really designed for.
Customer photos show the three colour-coded plates seated in the natural wood box with rubber mounts. Reviewers confirm durability across decades of use, and the practical advice that recurs is to buy a separate DMT base if you plan to work the stones outside the box.
The criticisms are all about the packaging rather than the abrasive. The plates sit in hollow plastic bases that can deform under heavy downward pressure. The stones slide around if you lift them out of the wood box. The lid has no latch. And the grit is identified only by colour code, with the labels printed on the reverse of the box cover, which is easy to miss the first time.
Why micron numbers beat grit numbers when you are buying
JIS grit numbers are a convenient label, not a measurement, and they assume a standard abrasive. Diamond is not that standard abrasive, so the honest spec is the micron figure. This set quotes 45, 25 and 9 micron across the three plates, which is a genuinely fine progression, and that is what tells you the extra fine side will refine rather than merely re-scratch.
Look for micron figures on any diamond plate you consider. Where a seller gives only a grit number, you are guessing at the real cutting speed and at the scratch depth, and on a hard steel edge the scratch depth is what determines whether your apex forms cleanly or chips.
Who should skip it
Skip the Deluxe kit if you need a large working surface, because 6 by 2 inch plates mean more repositioning on a chef’s knife. It is also the wrong value if you already own one good bench plate, since the two coarse-to-fine plates here overlap with what you have. And if your sharpening is occasional field touch-ups, this is a lot of kit to store.
12. RUIXIN PRO 8 Plate 100 to 3000 Set: the widest grit range, with the most caveats
RUIXIN PRO 8 Pcs Diamond Knife Sharpening Stones for RUIXIN PRO RX-008 RX-009 Knife Sharpener Fixed-Angle Kit, Professional Whetstone Set With Base: 100/200/500/800/1000/1500/2000/3000 Grit
Eight plates from 100 to 3000 grit
Set measures 7 by 6 by 0.3 inches, 0.39 kg
Designed for RUIXIN PRO RX-008 and RX-009 systems
Pros
- Eight grits including very coarse 100 and 200 for reprofiling hard steels
- Plates are well bonded and do not delaminate
- Faster cutting on steels hardened beyond RC60 such as M390
- Progression from 1000 to 3000 leaves few visible scratches after stropping
- Works with a fixed-angle system or as standalone hand stones
Cons
- Finer plates wear out relatively quickly compared with other brands
- Plastic bases can warp which changes the working angle
- Fine grits produce heavy residue and heavy scratches until broken in
- Some users report grit labels are not accurate to the actual abrasive
This is the only set here that can take a hard steel knife all the way from a wrong 30 degree bevel down to a near-mirror, because it spans 100, 200, 500, 800, 1000, 1500, 2000 and 3000 grit. The 100 and 200 plates are for reprofiling a badly neglected edge on something like an M390 or an S90V, where ordinary stones would take the better part of an hour and risk taking too much steel.
Users with steels hardened beyond RC60 report fast cutting and plates that are well bonded and do not delaminate. Owners with fixed-angle sharpening kits can use them in the RUIXIN PRO RX-008 or RX-009 system or standalone, and a light spray of water is recommended during use. The 1000 to 3000 end of the range leaves few visible scratches after a strop pass.
Customer photos show the eight small plates laid out with the base. The reviews are the most mixed in the roundup: this has the lowest rating at 4.3, the weakest five-star share at 69 percent, and the highest one-star share at 6 percent, which is a fair signal that something here frustrates a meaningful number of buyers.
Durability is the main complaint. The finer plates wear out noticeably faster than competing diamond, and the plastic bases can warp, which changes the angle you are working at partway through a session. Several users also break in the fine plates on cheap knives first, because at the start they mark edges heavily, and one blade-smith disputed whether the printed grit numbers match the actual abrasive.
When eight grit steps are worth the trade-offs
Eight steps earn their place in one specific situation: a knife that is at the wrong angle, has chips, or has not been sharpened in years, and is made of a steel that resists conventional stones. Starting at 100 or 200 grit on diamond removes metal quickly enough that the correction is not a nerve-wracking exercise, and stepping down through the range means the apex is refined rather than simply reached.
For anything less, the range is overkill. A sharpener who maintains a few knives weekly needs a coarse side and a fine side, not eight plates that all need storing, and the fine ones will thin out faster than the coarse ones, which leaves you with a set that is unevenly worn.
Who should skip it
Skip this set if you sharpen regularly, because the fine plates will wear out of step with the coarse ones and the warped bases will cost you angle consistency. It is a poor choice for someone who wants a mirror polish on a kitchen knife, since 3000 grit diamond does not get there. And anyone who is fussy about labelled accuracy should look elsewhere.
How to Choose a Diamond Whetstone: Grit, Bond and Steel
Start with the steel, not the stone. If your hardest steel is S90V, S35VN, M390, Maxamet, CPM 3V, HAP40 or Elmax, a diamond whetstone is not a luxury, it is the tool that will cut it. If your kit is MagnaCut, CruWear, 1095, 52100, or a German or Japanese kitchen knife, ordinary stones work, and diamond is simply faster rather than better. Experienced sharpeners on Chef’s Knives to Go are blunt about this, and the advice saves a lot of money.
Match grit to the job. A neglected edge that has not been touched in a year or more wants to start around 200 to 400 grit, move to 600 to 800 to set and refine the apex, and finish at 1000 to 1200 before a strop. An edge you maintain weekly needs only a fine side at 600 to 1200 plus leather. A chip or a damaged tip always sends you back to the coarsest plate you own, which is the main reason a two-sided plate is not enough for a hard steel collection.
Buy the micron figure, not just the grit number. JIS grit assumes aluminium oxide, so a diamond plate labelled 600 is not doing what an alumina stone labelled 600 does. The real purchasing spec is the micron average: 45 micron at 325 grit is coarse edge-setting work, 25 micron at 600 is honing, 15 micron at 1000 is refining, and 9 to 12 micron at 1200 is fine finishing. Where a listing gives you only a grit number, you are guessing.
Know the difference between a plate and a stone. A metal center plate has diamond electroplated onto a steel substrate. Particles stand proud of the surface, so the plate cuts deep and fast and can bite into the edge if you work at too high an angle. A resin-bonded diamond stone suspends the particles in a hardened resin, so they are less aggressive and rarely grab, which makes stones gentler on thin edges and on high angles. Vitrified diamond sits in between: a ceramic bond that stays flatter and lasts longer than resin, with a cut that is between the two. Every pick in this roundup except the goodjob three-sided stone is a metal center plate.
Monocrystalline versus polycrystalline. Mono diamond, used by DMT and by most of the plates here, is a single crystal with sharp natural facets that stay sharp as they wear. Polycrystalline diamond is a cluster of many tiny crystals that break down progressively, giving a more uniform but slightly slower cut. On hard steels, mono is the preference, and DMT is the reference standard in the forums.
Do not push, and do not buy a plate that ships inside a cheap sharpener. Electroplated diamond is held on by a thin metal layer, and heavy pressure accelerates the one failure mode these products have, which is particles shedding. Use light, consistent pressure and rotate the plate occasionally so it wears evenly. Separately, plates bundled with entry-level knife sharpeners are widely criticised as feeling gritty, shedding metal and never really improving, so treat them as a novelty rather than a tool.
Consider diamond paste before you buy a second plate. The most repeated answer on the forums is a pattern rather than a product: one 600 grit plate to apex, then 3 micron and 1 micron diamond paste worked into a leather strop to finish. It costs a fraction of a full stone set, it produces an edge that will shave, and it is the standard finish for an S90V or Maxamet. If you already own a good plate, this is the cheapest improvement available to you.
Expect a long life, and maintain it simply. Rinse, dry, store flat and never drop a plate on a hard floor, because a metal center plate is rigid and brittle. The abrasive is not renewable, so plate life is finite, but a plate used for a few knives a week rather than a production shop will outlast any consumable alternative. If you also own waterstones, a coarse diamond plate doubles as a lapping plate to keep them flat, provided you clean it thoroughly first.
If you are also replacing knives rather than stones this year, our picks in the best BBQ knives guide cover the outdoor side. The rest of a mixed workshop bench is just as fiddly, so our diamond painting accessories picks, the diamond painting kits roundup and the diamond painting storage cases guide cover the small-tool and storage side of the same setup.
Frequently Asked Questions
What are the best diamond whetstones?
The best all-round pick is the SHARPAL 162N, a flat 8 x 3 inch metal center plate with 325 grit at 45 micron on one side and 1200 grit at 12 micron on the other, rated 4.7 across more than four thousand reviews. For a portable option the SHARPAL 181N adds a cowhide strop, and for a pocket tool under one ounce the Smith’s DCS4 covers coarse and fine grits. The DMT Deluxe 3 stone kit is the best complete progression.
Are diamond whetstones better than waterstones?
On very hard, carbide-rich steels such as S90V, M390, Maxamet, CPM 3V and HAP40, yes. Diamond is harder than the carbides in those steels, so it shears them instead of skating off, and the plate stays flat where a waterstone dishes out. On soft steels like 1095, MagnaCut, CruWear and most kitchen knives, a good waterstone works well and diamond is only faster, not better.
What grit do I need for a hard steel knife?
For a neglected edge, start at 200 to 400 grit, refine at 600 to 800, finish at 1000 to 1200, then strop. For a routine weekly touch-up, a 600 to 1200 grit plate plus a leather strop is enough. Always check the micron figure as well as the grit number, because 45 micron, 25 micron, 15 micron and 12 micron correspond to 325, 600, 1000 and 1200 grit diamond.
How long do diamond whetstones last?
A metal center plate used for a few knives a week will last many years, and reviewers report plates still cutting well after a decade. Life is lost to heavy pressure, which dislodges electroplated particles, and to fine plates worn down by high-volume work. A resin-bonded stone wears faster but is gentler on thin edges. Store plates flat, rinse and dry them, and never drop one on a hard floor.
Are Atoma and DMT diamond stones good for hard steel?
Both are repeatedly named as the reference points for hard steel on the sharpening forums. DMT plates use micronized monocrystalline diamond in a sprinkled, very uniform coating, while Atoma plates use a clustered construction, and both cut S90V and M390 effectively. SHARPAL and Smith’s plates are the value alternatives, using monocrystalline diamond at a lower cost with somewhat more variation in particle exposure.
Conclusion: The Right Diamond Whetstone for Your Steel
The best diamond whetstone for hard steel knives is the one that stays flat, quotes its micron size and covers the grits you actually need. For most people that is the SHARPAL 162N, with a 325 grit side for resetting an edge and a 1200 grit side for finishing on a plate big enough to work a full chef’s knife. If you travel, the SHARPAL 181N folds the same grits and a strop into one object, and if you want a complete progression in one box, the DMT Deluxe kit runs 45, 25 and 9 micron from coarse to polish.
Start with your steel, not the marketing. Diamond earns its place on S90V, M390, Maxamet, 3V and Elmax and is merely convenient on MagnaCut, CruWear and 1095. Check the micron figure, keep the pressure light, and add a loaded strop to finish. Those three habits will get more out of any plate on this list than the brand name ever will.