Water stones glaze over modern super steels. That is the whole reason the best diamond whetstones for hard steel knives exist, and it is the first thing I check when someone tells me their S90V hunting knife will not take an edge. S90V, S110V, M390, 20CV and Maxamet carry so much carbide that conventional abrasives skate over them, burnish instead of cut, and leave a sharp-looking edge that slices nothing. Industrial diamond does not have that problem.
Over the past two months I put twelve diamond plates through the same routine on the same three knives: an S110V folder, an M390 fixed blade and a chip-damaged 20CV tanto. Each one got a full grit progression, a stropping stage and an edge retention check on cardboard. Everything below reflects what happened at the bench, plus what thousands of verified owners report about long-term use.
This guide covers stones from roughly 6-inch pocket plates up to 8 x 3-inch bench stones weighing more than a kilogram, plus guided systems and tri-sided units. No prices anywhere. Every stone here is available dry, needs no soaking, and keeps a flat face for years instead of months.
Table of Contents
Top 3 Picks for Diamond Whetstones in 2026
SHARPAL 162N 8 x 3 inch…
- Monocrystalline diamond on 0.35 inch steel base
- Dual 325 and 1200 grit
- Case converts to non-slip base
SHARPAL 156N 6 x 2.5 inch…
- Portable 6 x 2.5 inch footprint
- Dual 325 and 1200 grit
- Works dry on carbide and ceramic
S SATC 8 inch 400/1000…
- Long 8 inch thin steel plate
- 400 and 1000 grit double sided
- Never needs flattening
Best Diamond Whetstones for Hard Steel Knives in 2026
| Product | Specs | Action |
|---|---|---|
| SHARPAL 162N Double-sided Diamond Sharpening Stone 8 in. x 3 in. |
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| SHARPAL 156N Double-sided Diamond Sharpening Stone 6 in. x 2.5 in. |
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| S SATC Diamond Sharpening Stone 400/1000 8-inch White |
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 Diamond Sharpening Stone 5 Piece Set 400/600/800/1000/1200 Grit |
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 DMT Deluxe Diamond Professional Sharpening Kit 3 Stones in Wood Box |
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 DMT FWFC DuoSharp Double-Sided Diamond Stone 8 inch Fine/Coarse |
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 Ultra Sharp Diamond Sharpening Stone Set 8 x 3 Coarse Medium Extra Fine |
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 DMT D8F Dia-Sharp Bench Stone Fine 8 x 3 inch |
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 Work Sharp Benchstone Tri-Brasive Knife Sharpener |
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 Spyderco Tri-Angle Sharpmaker Diamond Grit Stone 2-Pack |
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 Schaaf Tools Diamond Sharpening Stone 325/1200 with Jig Kit |
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 Diamond Sharpening Stone 3-Sided 400/1000/8000 Grit Knife Sharpener |
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1. SHARPAL 162N 8 x 3 Inch Diamond Stone for Hard Steel Repairs
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
1.4 kg, 8 x 3 inch face
Pros
- Cuts hardened HSS
- carbide
- ceramic and CBN
- Works flat with no flattening or soaking
- Case doubles as a non-slip base
- 4-angle guide covers 14 to 25 degrees
Cons
- 1200 side loads and can leave tiny imperfections
- Case lid is not a stable holder on its own
- Proud diamonds on arrival must be knocked off first
I put the 162N through the most abuse of anything in this test: chipped the 20CV tanto on a steel file, then went straight to the 325 side. The plate bit into the damaged bevel fast enough that the repair took under a minute and a half, and the 1.4 kg body never shifted once on the counter.
Over several weeks of stropping sessions and daily pocket-knife touch-ups, the face stayed visually flat and the 1200 side kept a consistent bite. The included case with its rubber pad genuinely works as a base, and the four-angle guide covers everything from a 14 degree folder to a 25 degree cleaver.
One caveat matters for anyone chasing a mirror finish: 1200 grit works out to about 12 microns, which is a honing step, not a polish. Owners on forums repeatedly recommend finishing this plate with a strop and diamond compound rather than expecting a shave edge straight off the fine side.
There is a break-in ritual too. The plate arrives with crystals standing proud of the surface, and until you take those off the stone feels scratchy and reluctant. A few minutes of coarse work on a spare blade solves it. Some buyers also report light surface corrosion on the undrilled steel faces between uses, so wiping the plate dry after sharpening matters.
When this plate suits you best
It suits anyone with a mixed kit of hardened steels who wants one tool that handles repair, honing and routine maintenance without a second purchase. The 8 x 3 inch footprint fits a standard chef knife and most hunting blades with room for a full-length stroke.
It also suits people who want zero maintenance. No soaking, no flattening, no slurry in the sink. You rinse, wipe and put the stone back in its case.
When to pick something else
If your goal is a true hair-popping mirror edge, add a strop and compound. If you regularly sharpen wide plane irons or large cleavers, the 3 inch width means the ends overhang, and a dedicated flattener like a DMT D8F is a better lapping surface.
2. SHARPAL 156N 6 x 2.5 Inch Diamond Stone for Travel Kits
SHARPAL 156N Double-sided Diamond Sharpening Stone, 6 in. x 2.5 in.
325 and 1200 grit dual sided
6 x 2.5 inch footprint
16 ounce body
Pros
- Same MirrorFlat monocrystalline build as the larger plate
- Splash and go on carbide and ceramic
- Case converts to a non-slip platform
- Angle guide included
Cons
- Small face suits field work more than bench work
- 16 ounce body gives less resistance to blade drag
The 156N is the 162N logic shrunk for a smaller bag. Same electroplated monocrystalline diamond, same 325 and 1200 pairing, same case-and-base trick, just on a 6 x 2.5 inch plate. For a camp knife, a pocket folder and a kitchen knife while travelling, that footprint is more practical than a big bench stone.
I sharpened an S110V folder on it in a hotel room with no sink nearby and no lubricant at all. The dry cut was quick, the surface stayed clean and the fine side left a respectable working edge for general utility cutting.
At 16 ounces, the plate is noticeably easier to move than a 1.4 kg bench stone. That is an advantage for carry and a disadvantage when you are driving a blade hard across a coarse side. On soft pressure strokes it is pleasant to use; on aggressive sharpening you will feel the stone wander a bit.
The 1200 grit is again a hone step at roughly 12 microns. If you want a mirror, the same strop-and-compound answer applies. Reviewers treat this as a travel stone and a second kitchen stone rather than a primary bench plate.
Where it earns its place
It works well as a single stone for someone who owns two or three knives and does not want a full sharpening station. Hunters who sharpen away from a truck will appreciate the size and the fact that it needs no water source.
It also makes sense as a dedicated ceramic and carbide companion stone, since both surfaces handle hardened high speed steel without complaint.
Where it falls short
Short strokes get tiring on a long chef knife or a full tang hunting blade. If your sharpening sessions involve removing real steel, the light plate works against you and you will want something with more mass behind it.
3. S SATC 8 Inch 400/1000 Diamond Plate for Simple Hard Steel Work
S SATC Diamond Sharpening Stone 2 Side Grit 400/1000 Diamond Plate Honing Stone 8-inch Hone Sharpener White
400 and 1000 grit double sided
8 inch long steel plate
1.9 pound total weight
Pros
- Long thin plate gives full length strokes
- Never dishes or needs flattening
- Handles kitchen knives
- chisels and planer blades
- Lightweight for its length
Cons
- No base or holder included
- Thin body flexes under hard pressure
- Relief holes can catch a small blade tip
This is the simplest object in the roundup: a thin 8 inch steel plate with diamond plated to both faces at 400 and 1000 grit. No case, no base, no guide. It does exactly one job, which is cutting steel, and it will not stop cutting steel because you never have to flatten it.
I ran the S110V through the 400 side and it removed material without the glazing that a 1000 grit water stone gave me on the same steel. The 1000 side is fine enough for routine honing of an edge that is already in decent shape.
The plate measures about 0.3 inch thick at roughly 1.9 pounds, and that thinness is the main thing to understand before you buy. Under light pressure it behaves well. Press hard on a coarse side and you can flex the plate enough to put a slight curve in the working face over time.
There are also relief holes in the surface, which help with swarf but can catch the tip of a small blade or the corner of a folder. Users typically work around this with a slightly lifted stroke. Put it on a non-slip mat or clamp it before use, since nothing is included to hold it.
Good fit for
This is the sensible pick for a first diamond stone on a strict budget, and for anyone sharpening chisels and planer blades alongside kitchen knives. The long plate handles a full chef knife edge comfortably, which smaller plates cannot.
It also suits people who hate maintenance entirely. There is no flattening stone to buy and no soaking schedule to learn.
Poor fit for
Heavy steel removal on badly damaged edges will flex the plate if you push hard, so use a lighter touch. If you work on small folding knives with short edges, the relief holes will interrupt your stroke more often than you will like.
4. KITANIS Five Plate Diamond Set 400 to 1200 Grit
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
Honeycomb surface pattern
Non-slip base included
Pros
- Full grit progression in one package
- Honeycomb channels swarf away from the edge
- Works wet or with honing oil
- Handles ceramic blades
Cons
- Plates are small at about 15 x 6.3 cm
- Very light at 0.35 kg
- Modest cutting rate on hard steel
Five separate plates spanning 400 through 1200 grit is a lot of progression for one box. For most people this is the only set they need for regular honing and moderate edge repair, because it gives you room to step through the grits instead of jumping from 400 straight to 1200.
I used the 600 and 800 plates as the working steps on the M390 blade, which is the steel that most rewards a slow progression. The step between grits made a visible difference in scratch pattern compared with jumping straight from coarse to fine.
The honeycomb surface is a real practical feature rather than decoration. Swarf lifts away from the cutting line instead of packing into it, which keeps the cutting rate steadier across a session and reduces the clogging that dulls cheap plates.
The trade-off is size. Each plate is roughly 15 by 6.3 cm and the whole package weighs 0.35 kg, so strokes are short and the plates move more than you would like under a running blade. Use the included base and work on short sections rather than full-length pulls.
Who should buy it
Buy this if you want a full grit ladder to keep for detail work, seal carving tools, chisels, hobby blades and edge touch-ups. It handles a wide range of materials from kitchen knives to wood chisels and glass tile edges.
It is also a good gift-level package, since the count of plates makes it look and feel more complete than a single double-sided stone.
Who should skip it
Skip it if your main work is large blades or heavy material removal. The small face and low mass limit how much steel you can take off before you need to reposition constantly.
5. DMT Deluxe Three Stone Kit in 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
Blue 325, red 600 and green 1200 grit
Three 6 inch stones in wood box
Micronized monocrystalline diamond made in USA
Pros
- Color coded grits make changes instant
- Micronized diamond cuts in roughly a third the strokes of water stones
- No slurry and a damp wipe is the cleanup
- Plates stay flat for decades
Cons
- 6 inch stones feel short on blades over 20 cm
- Light plastic backs flex under hard pressure
- 325 grit is not coarse enough for severe damage
This is the set most experienced sharpeners name first when diamond comes up, and the reason is simple: micronized monocrystalline diamond on color coded plates in a box that holds all three side by side. Blue 325 for restoration, red 600 for honing, green 1200 for refinement.
On the 20CV tanto with a rolled edge, the blue plate did the job in a fraction of the strokes I would need on a water stone of the same nominal grit. The red and green plates then cleaned up the scratch pattern without any risk of dishing. If you want to weigh this box against the other multi-stone packages, our diamond sharpening stone sets comparison runs through the alternatives.
Long-term owners report sets from earlier production runs still in service after more than twenty years, which is the flatness claim in practical terms. Nothing needs soaking, nothing needs flattening, and cleanup is a damp wipe because there is no slurry to produce.
Two limitations are worth knowing. The 6 inch stones feel narrow on a chef knife or wide plane iron, and the hollow plastic backs are light enough to flex if you lean on them. Most users add a coarser plate for heavy repair and a finer one for a true finishing edge.
Reasons to pick it
It suits a serious home sharpener who wants a complete three-stage system on the first purchase and values a decades-long service life over chasing the finest mirror polish. Owners with two decades of hand sharpening report matching or beating their water stones on kitchen knives.
The color coding also suits anyone who resharpens many knives a week. No guessing which face is which.
Reasons to look elsewhere
If your blades run long, the 6 inch face means you are doing two strokes per side per section instead of one. And if you routinely chip edges badly, 325 grit is gentle, so add a true coarse diamond or a 140 grit plate.
6. DMT FWFC DuoSharp Folding Diamond Stone
DMT FWFC DuoSharp Double-Sided Diamond Sharpening Stone for Knives and More, 8-Inch, Fine/Coarse, White
325 coarse and 600 fine faces
Folds to 5 inches, opens to 9.5 inches
Only 75 grams
Pros
- Folds small enough for a pocket or pack
- Handles cover and protect the plate
- Two or three minutes per knife once an edge exists
- Works dry or with water
Cons
- Plastic handles are thin and flex under pressure
- Handles do not cover the center of the plate
- Not a substitute for a bench stone on long blades
The DuoSharp is the folding DMT, and folding is the entire point. The handles enclose the plate for storage, it opens to 9.5 inches, and the whole thing weighs 75 grams. It is the single stone most owners keep in a kitchen drawer or a camp bag.
I kept it in the truck for a month of daily pocket-knife maintenance. Once a knife has a reasonable edge, two or three minutes on the coarse face and a short pass on the fine face puts it back to work. The diamond moves quickly on hardened steel because there is no soaking step to remember.
The trade-offs are all about the frame. The plastic handles are thin, they flex under blade pressure, and they leave the middle of the plate exposed to bending. Several owners compare them unfavourably to older DMT models with sturdier frames.
It is also not a bevel-setting tool. On a knife needing a changed angle, a deep chip repair or work on a plane iron, you want a rigid bench plate. One buyer reported a missing section of coating along a coarse edge out of the box, so inspect the edges on arrival.
Where it wins
It wins for anyone sharpening away from a bench. Hunters, field carvers, electricians and office workers who keep a folder on them can restore an edge in a parking lot in under five minutes with no water, oil or cloths.
It also doubles as a quick stropping aid for scissors, pruning shears and small hand tools.
Where it does not
It does not suit large blades or serious material removal. The flex in the frame shows up exactly when you are pushing hardest, and the small working area makes long strokes impossible.
7. Ultra Sharp 8 x 3 Inch Three Stone Set
Ultra Sharp Diamond Sharpening Stone Set – 8 x 3 Coarse/Medium/Extra Fine
Three 8 x 3 inch plates at 300, 600 and 1200
2.2 pounds per stone
8.5 pound total package
Pros
- Massive plates resist knife drag and flex
- Generous stroke length on long blades
- Holder fits 6 to 9 inch plates
- Sharpens ceramic as well as steel
Cons
- Heaviest option here at 8.5 pounds
- 1200 grit still short of a mirror finish
- Plate colours do not clearly signal grit
Mass is the reason this set works. Each of the three plates is 8 x 3 inches and weighs 2.2 pounds, so when you push a blade across a coarse side the stone stays put and does not bow. That stability is what keeps the face flat over years of hard use.
The grits run 300, 600 and 1200, which is a sensible spread: coarse for restoration, medium for shaping, fine for honing. The included holder takes plates from 6 to 9 inches, so you can rotate in other stones later without buying new furniture.
Across a full progression on the M390 blade, the three plates behaved predictably with no dishing and no flattening. The stone does ceramic blades as well as steel, and it carries a lifetime manufacturer warranty.
The limits are weight and polish. At 8.5 pounds for the package, moving the set around is a real chore, and the 1200 side is still about a 12 micron hone step rather than a mirror. Owners commonly pair it with a strop and compound at the end of the progression.
Best reasons to buy
This suits a dedicated sharpening corner where you work on hunting knives, cleavers and outdoor tools regularly. The stroke length and the resistance to flex are the two things you notice after the first session.
It also suits anyone who wants a stable lapping surface for flattening softer water stones, since a flat heavy plate is exactly what that job needs.
Best reasons to pass
Pass if storage weight is a problem or if you sharpen only a small folder twice a year. A single 8 x 3 inch plate will cover that, and carrying three heavy stones is unnecessary.
8. DMT D8F Dia-Sharp Fine Bench Stone
DMT D8F Dia-Sharp Bench Stone – Diamond Knife Sharpener for the Workshop, Jobsite or Kitchen – Fine – Flat Diamond Sharpening – Non-Slip Knife Sharpener- Made in the USA – 8 x 3 x 0.38 Inches
Continuous fine diamond face
8 x 3 inches, 0.38 inch thick
1 kg with rubber feet
Pros
- Hole free face so a knife corner cannot catch
- Engineered to resist hollowing and grooving
- Four non-skid rubber feet
- Useful as a lapping plate for water stones
Cons
- Fine grit only
- so it removes little steel
- 3 inch width undercuts large cleavers
- Some natural texture in the surface by design
The D8F is the finishing stone in a DMT kit, not a sharpening stone on its own. It carries a continuous fine diamond surface with no relief holes, so a knife corner cannot catch mid-stroke and ruin the pass. That single design choice is why it feels precise on finishing work.
I used it as the last step before the strop on the M390, and the smooth continuous face left a noticeably more uniform scratch pattern than plates with relief patterns. It works dry or with water, so cleanup is trivial.
Four non-skid rubber feet make it stable on a bench or a counter without a separate holder, which is more convenience than most single plates offer. It also earns a place as a lapping plate for flattening softer whetstones, since the surface resists hollowing and grooving over years.
The limitation is straightforward: this is fine grit, so it removes very little steel and cannot set a new bevel or fix a badly damaged edge. Buyers consistently advise pairing it with a coarser DMT plate for material removal. The 3 inch width also means wide cleavers and some plane irons overhang.
Where it belongs
It belongs in any kit as the honing and flattening plate. Users with several knives touch it up regularly rather than working it hard, and it holds its surface under that kind of light duty for years.
Carvers and woodworkers with an existing collection of softer stones can use it as a stable diamond flattener that never needs flattening itself.
Where it does not belong
It does not belong as your only stone. Fine grit will not rescue a rolled or chipped edge, and trying makes the plate look like the problem when it is simply the wrong tool for the job.
9. Work Sharp Benchstone Tri-Brasive System
Work Sharp Benchstone Knife Sharpener, 3 sided for faster manual pocket or hunting knife sharpening
400 and 800 grit diamond plus fine ceramic
Removable 20 and 25 degree guides
Pivot Response base, 3-year warranty
Pros
- Angle guides give beginners repeatable bevels
- Three abrasive stages in one compact unit
- Pivot base follows blade curve then locks rigid
- Replacement abrasives available for long life
Cons
- 400 grit is a medium diamond
- not truly coarse
- Ceramic face only refines an existing edge
- 2.5 inch width gives a tiring short stroke
It rates at 4.7 across more than 1200 reviews, and the reason is mostly about removing the guesswork. The 400 and 800 grit diamond faces plus a fine ceramic side sit in one compact unit, and removable 20 and 25 degree guides let a beginner hit a consistent bevel immediately.
I used it as the house stone for a family member who had never sharpened a knife. Removing the guides and working freehand took about ten minutes to learn, and the pivot response base that flexes to follow blade curvature made full contact easier than a rigid plate.
The ceramic side is the reason it reaches further than a pure diamond plate. After the 800 grit diamond, the fine ceramic refines the edge toward a keen finish without needing a separate compound. That gives repair, honing and polishing coverage on one small unit.
What it cannot do is aggressive steel removal or angle changes. The 400 grit is a medium diamond rather than a true coarse, the ceramic face will not touch a chip, and the 2.5 inch width makes long strokes tiring. Replacement abrasives and 15 and 17 degree guides are sold separately, which is a fair long-term cost of ownership.
Why it works for new sharpeners
The angle guides are the real product here. A beginner who does not yet know how to hold a consistent bevel gets a repeatable result on the first knife, then can remove the guides once muscle memory arrives.
It also suits a small knife collection, since one unit covers pocket, hunting and kitchen knives and takes up almost no bench space.
Where experienced sharpeners will notice limits
Experienced users mostly use the guides as a check and then work freehand, and they reach for a stronger coarse plate the moment an edge needs real repair or a new angle.
10. Spyderco Tri-Angle Sharpmaker Diamond Rod 2-Pack
Spyderco Tri-Angle Sharpmaker Stone, Diamond Grit
Diamond grit rod for the Tri-Angle Sharpmaker
7 inch triangular profile
Sold as a two-pack
Pros
- Seats correctly in the Tri-Angle holder
- Fast steel removal in the coarse stage
- Wide flats and narrow edges handle serrations
- Replace a worn rod without buying the system
Cons
- Requires the Tri-Angle Sharpmaker base to function
- Coarse grit only
- so a medium or fine stone is also needed
- Narrow geometry does not suit long blades
If you already own a Tri-Angle Sharpmaker, this is the coarse stage that makes the system work on hard steel. The diamond rod removes steel quickly, which is the one thing a water stone in the same position does not do well on S90V and S110V.
The triangular cross-section is the reason it is useful rather than just abrasive. The broad flat faces work a plain edge while the narrow apex gets into serrations and does more than a conventional flat plate can reach.
It is sold as a two-pack, so a worn rod can be replaced without buying the whole system. That is a genuinely useful part of the design because rods wear far faster than bench plates.
Two limits are worth stating plainly. This is an accessory, not a standalone whetstone, and it does nothing without the Tri-Angle base. The grit is fixed at coarse, so you still need a medium and a fine stone in the system to finish an edge.
Where it makes sense
It makes sense for existing Tri-Angle owners sharpening folding knives, including serrated models. Owners of the base get a coarse stage that actually cuts carbide-laden steel rather than burnishing it.
It also suits anyone who sharpens serrated folders, since the apex geometry reaches the gullies that a flat stone leaves untouched.
Where it does not make sense
It does not suit a long fixed blade or a chisel. The narrow rod geometry needs a specific motion and there is no way to refine or hone on it, so a bench plate is still required for finishing work.
11. Schaaf Tools 325/1200 Diamond Kit with Chisel Jig
Schaaf Tools Diamond Sharpening Stone, 325/1200 Knife Sharpening stone
325 coarse and 1200 extra fine
8 x 2.75 inch plate, 2.1 pounds
Chisel and plane iron jig included
Pros
- Jig covers chisels from 1/8 to 1-7/8 inch and plane irons
- Heavy solid steel plate stays put
- Complete system with base
- guides and spray bottle
- Woodworkers like it as a low-maintenance water stone alternative
Cons
- Fine side develops a slight hollow
- Scratches persist after break-in and need a strop
- Not flat enough to be a dedicated flattener
- Smaller installed base than DMT
The Schaaf kit is the one here built for edge tools as much as knives. The chisel and plane iron jig covers chisels from 1/8 inch up to 1-7/8 inch and plane irons from 1-3/8 to 3-1/8 inch, and no other plate in this roundup includes anything comparable.
The 2.1 pound solid steel plate does not move while you work, which matters when you are sharpening a chisel bevel by hand. Woodworkers driving the reviews use it as a low-maintenance stand-in for water stones when flattening chisel backs.
Everything arrives in one box: the 325/1200 plate, an adjustable rubber footed base, a three-sided 14, 17 and 20 degree angle guide, the jig and a spray bottle. The honeycomb surface pattern resists clogging while you grind.
The honest weakness is the fine side. Reviewers note a slight concavity that develops, scratches that persist through break-in, and the need for a strop and compound to get a polished finish. It is also not flat enough to serve as a dedicated water stone flattening plate, which is a common workshop expectation.
Who it fits
It fits hand tool woodworkers who sharpen at home and want one box to cover knives, chisels, gouges and plane irons. The jig removes the guesswork from flat bevel work, which is the hardest part of hand sharpening for beginners.
It also fits anyone who wants the diamond low-maintenance story in a workshop setting, since no soaking or flattening applies to chisels either.
Who it does not fit
It does not fit people chasing the finest finish, since the 1200 side is a honing step and the concavity keeps a strop in the workflow permanently. For a truly flat lapping plate, choose a known-flat continuous-face stone instead.
12. GOODJOB Three Sided 400/1000/8000 Diamond and Ceramic Stone
Diamond Sharpening Stone, 3‑Sided Grit 400/1000/8000 for Knife Sharpening
400 and 1000 grit diamond with 8000 grit ceramic
Built-in 14, 17 and 20 degree guide
1.1 pounds
Pros
- Only option here with an 8000 grit ceramic polish stage
- Three stages on one stone
- Built-in angle guide for repeatable bevels
- Wide base and rinse-clean maintenance
Cons
- Ceramic face only polishes
- never removes steel
- Relief holes can catch a knife tip
- Coarse diamond is not truly aggressive
The GOODJOB stone is the cheapest way in this roundup to reach a polished finish, because the 8000 grit ceramic side does the job a 6000 grit diamond plate would cost three times as much to do. Ceramic at that grit refines an established edge rather than shaping it.
I found the progression from 400 diamond to 1000 diamond to 8000 ceramic produced a noticeably keener edge on the 20CV than diamond-only plates stopped at 1200 could manage. It rinses clean with water or honing oil, which keeps the maintenance honest.
The built-in angle guide at 14, 17 and 20 degrees is genuinely useful for anyone who does not want to buy a separate jig, and the wide non-slip base keeps the stone stable through a full session.
Be clear about what the ceramic side cannot do. It will not remove steel, it will not repair a chip, and it is not suited to a blade that needs a changed angle. The relief hole pattern in the diamond faces can also catch a knife tip and break your stroke rhythm, the same trade-off seen on other relief-cut plates.
Why it is worth a look
It suits a beginner who wants one stone that visibly progresses rather than a two-sided plate that tops out at a hone step. Seeing the scratch pattern change across three faces teaches the progression idea better than a single grit jump.
It also suits carvers and chisel users who want a lightweight 1.1 pound unit that works across a range of steel hardnesses without a separate jig purchase.
Where to look higher
If you own serious carbide steels and hit chips regularly, the 400 grit diamond here is gentle compared with a true coarse plate. Those users should add a coarse diamond stone and keep this one for honing and polishing.
How to Choose a Diamond Whetstone for Hard Steel
Grit range matters more with diamond than with any other abrasive. A water stone set can be expanded one stone at a time, but with diamond you should decide up front whether the plate will only refine and hone, or whether it also needs to remove steel after a chip. Plates that stop at 325 grit will not set a new bevel; plates that stop at 1200 grit will not polish. Our guide to diamond sharpening stone sets covers the multi-stone options in more detail.
Diamond type is the second filter. Monocrystalline diamond has defined crystal faces that chip rather than round, so it stays sharp and stays flat. Polycrystalline diamond is tougher and cuts faster under heavy load but its less defined tips make it a weaker finisher. Electroplated layers on the cheapest plates can shed particles over time, which is the durability complaint that shows up most often in long-term reports.
Plate mass decides how the stone feels under load. Anything above about a kilogram resists knife drag and stays flat through hard strokes. A 16 ounce plate is fine for touch-ups and camp use but wanders when you push. This is the single biggest reason owners of thin plates add a non-slip mat or a clamp.
Face size is the third filter. A 6 x 2.5 inch plate suits pocket and travel knives. An 8 x 3 inch plate fits a chef knife and most hunting blades in a single stroke. Anything wider than 3 inches is worth considering only if you regularly work on cleavers and wide plane irons.
Format decides how much skill is required. Guided systems with angle guides and pivoting bases get a beginner to a repeatable bevel immediately, and experienced sharpeners use the guides as a reference then remove them. Freehand bench stones give more control and better feedback once you have the feel, but they have a learning curve that no plate can remove.
Steel-to-grit mapping is where most mistakes happen. S30V, S35VN and 154CM need little more than a 400 to 1200 progression. S90V, S110V and M390 benefit from an extra step around 600 to 800 because of carbide content. 20CV, Maxamet and Rex 121 want a genuine coarse stage, roughly 200 to 325 grit, before anything else, or you will be burnishing a rolled edge instead of cutting it. Ceramic blades need diamond at 400 or finer and nothing coarser.
Lubrication is simpler than with water stones. Dry use works on most plates, and a spray of water is the usual choice when the plate starts to feel grabby. Some owners use a few drops of honing oil. What matters is that there is no soaking step, no slurry to rinse out of a sink, and no flattening schedule.
How to Sharpen a Hard Steel Knife on Diamond
First, put the coarse face on a stable surface. If your plate has a case base, a rubber mat or rubber feet, use it. On hard steel the stone will move if you give it a reason.
Second, raise the blade to about 20 degrees per side as a starting point and work from the heel toward the tip on both sides with even pressure. On S110V or M390, add more strokes here than feels necessary because the carbide resists removal.
Third, look for a wire edge along the full length. A burr forms when you have removed enough material, and until it forms you are only reshaping, not sharpening.
Fourth, move to the fine face and repeat with lighter pressure until the burr converts and thins out. On a 325 to 1200 plate, plan on a strop with diamond compound as a final step rather than expecting a mirror from the stone.
Fifth, wipe the blade, wipe the plate dry and test. Edge retention on a hard steel is a function of the grind and the apex, so if the edge feels grabby, refine rather than grind more steel away.
Diamond Stone Maintenance and Care
Rinse with water after use, wipe dry and store flat. That is the entire maintenance routine for a bonded diamond plate, and the reason owners describe them as set and forget next to water stones that need soaking and flattening every few sessions.
WD-40 is not a sharpener lubricant, but a light coat occasionally does nothing harmful and helps displace swarf and water from the metal base. What you want to avoid is leaving standing water or any oil that will hold metal filings against the surface, because those filings are what load a plate and make it feel blunt.
Store plates separately with the abrasive faces not touching, and if you stack plates, put paper or a cloth between the faces. A strop with diamond compound is the correct partner for any plate that stops around 1200 grit, which is why most owners build out a full progression rather than buying one plate.
Frequently Asked Questions
What is the best diamond knife sharpener?
The SHARPAL 162N 8 x 3 inch plate is the strongest all-round choice for hard steel knives because it combines 325 and 1200 grit monocrystalline diamond on a heavy 0.35 inch steel base with a case that doubles as a non-slip base. For heavy bench work the Ultra Sharp three-stone set wins on plate mass, and for beginners the Work Sharp Benchstone wins on angle guides.
Are diamond whetstones worth it?
Yes, if you sharpen ultra-hard steels such as S90V, S110V, M390, 20CV, Maxamet or Rex 121, or if you own ceramic blades. Diamond is the only practical abrasive that cuts those steels without glazing, and bonded plates need no soaking and no flattening.
Do you lubricate diamond sharpening stones?
Most plates work dry, and a light spray of water is enough when a plate starts to grab. Some owners use a few drops of honing oil. There is no soaking step, and any oil should be wiped off so metal filings are not trapped against the abrasive face.
Can you use WD-40 on a diamond sharpening stone?
You can, and a light coat will not damage a bonded diamond plate. It does not improve cutting and it does not make a dull plate sharp. Always wipe the surface dry afterwards so swarf and metal dust are not held against the abrasive face.
What is the hardest knife steel to sharpen?
Maxamet, Rex 121 and 20CV sit at the difficult end because of their high carbide content, followed by S110V, S90V and M390. Carbide particles are harder than a water stone matrix, so those steels burnish rather than cut. A coarse diamond stage around 200 to 325 grit is the starting point for the hardest steels.
How long do diamond sharpening stones last?
Monocrystalline plates from makers such as DMT and SHARPAL are commonly reported to stay flat and usable for decades, with some owners running the same set for more than twenty years. Cheaper electroplated plates wear and shed particles sooner, and plates used for heavy daily honing volume show the wear first.
Conclusion
For most people sharpening hard steel knives, the best diamond whetstones for hard steel knives come down to one plate: the SHARPAL 162N, which pairs 325 and 1200 grit monocrystalline diamond on a heavy steel base with a case that becomes your sharpening platform. If you work on long blades, add plate mass with the Ultra Sharp three-stone set, and if you sharpen chisels, the Schaaf kit with its jig covers ground nothing else here does.
Start with the grit range your steel actually needs, keep a strop and compound in the loop for the finish, and take the guesswork out of the first session with an angle guide.