Buy the SHARPAL 162N if you want one diamond plate for knives and tools: it's 8 by 3 inches, coarse on one side and extra-fine on the other, and it's one of Amazon's best-selling sharpening stones. Buy the DMT Diafold if you'd rather have a US-made folding plate, and the Ultra Sharp three-stone set if you sharpen a lot of different blades. A diamond plate is the right tool for hard modern steels, flattening water stones and dinged-up tools. If your knives are soft German stainless, read the who should skip diamond section before you buy.
Quick picks
| Best overall | SHARPAL 162N Diamond Plate (8 x 3 in) | Amazon |
|---|---|---|
| Best made-in-USA plate | DMT FWFC Diafold (fine/coarse) | Amazon |
| Best set | Ultra Sharp 3-Stone Diamond Set | Amazon |
| Best for flattening water stones | Atoma #400 Diamond Plate | Amazon |
| Best diamond stone that feels like a whetstone | Naniwa Diamond Whetstone #1000 | Amazon |
| Best pocket plate | Smith's DCS4 4-inch Diamond Combination | Amazon |
| Best for wallets and travel | DMT Dia-Sharp Credit Card Set (3) | Amazon |
How we picked
We searched Amazon for diamond sharpening stones and plates on October 13, 2026, keeping products with real sales and long rating histories: the SHARPAL 162N showed 1,000+ purchases in the past month and ranked #2 in Amazon's honing stones category. We then read the makers' own specs (micron sizes, surface type, plate size) from each listing, plus DMT's published FAQ for care and grit sizes, and the most useful owner discussion we found, a long Kitchen Knife Forums thread on diamond plates for hard steels.
This page is a How we pick review. We compared listings with manufacturer guidance and owner reports; we didn't run our own sharpening tests on these stones. How we research.
What diamond grit numbers mean
Diamond plates are sold by mesh (a sieve size) or micron (the particle size), and the two don't always line up from brand to brand. The micron number is the honest one. DMT publishes its full ladder:
| DMT grade (color) | Diamond size | Mesh | Use it for |
|---|---|---|---|
| Extra-extra coarse (silver) | 120 micron | 120 | Flattening water and Arkansas stones |
| Extra-coarse (black) | 60 micron | 220 | Axes, mower blades, reshaping a broken tip |
| Coarse (blue) | 45 micron | 325 | Restoring a dull or chipped knife |
| Fine (red) | 25 micron | 600 | Routine sharpening of a working edge |
| Extra-fine (green) | 9 micron | 1200 | Refining; a good kitchen finish |
| Medium extra-fine | 6 micron | 4000 | A finer finish before polishing (sold as the D8ME bench stone) |
| Extra-extra fine (tan) | 3 micron | 8000 | Polishing |
Here's where it gets confusing: SHARPAL also calls its fine side "1200 grit" but lists it at 12 micron, a bit coarser than DMT's 9 micron 1200. Neither is wrong; they're different labels for a similar grade. And none of these numbers line up neatly with the JIS grit printed on Japanese water stones, so a "1000" diamond plate and a "1000" water stone don't leave the same edge. Our sharpening stone grit chart covers the conversions that makers publish.
Who needs diamond, and who should skip it
| What you sharpen | Diamond plate? | Why |
|---|---|---|
| High-vanadium stainless (S30V, S90V, MagnaCut, M390) | Yes | Hard carbides cut slowly on ordinary stones; owners on Kitchen Knife Forums use diamonds through the whole progression |
| Ceramic knives, carbide or high-speed steel tools | Yes | SHARPAL lists ceramic, carbide and HSS among the materials its plates handle |
| Axes, machetes, garden tools | Yes, coarse | Fast metal removal and no soaking in the field; see how to sharpen an axe |
| Flattening water stones | Yes, coarse | The plate stays flat; see how to flatten a whetstone |
| Soft German stainless (Wüsthof, Zwilling, Victorinox) | Optional | Water stones cut these fine and leave a smoother edge |
| Carbon-steel Japanese knives | Coarse only | A water stone finish suits them better; see Japanese whetstones |
If you're stuck between the two, our whetstone vs diamond stone comparison goes through feel and upkeep in detail. Ceramic knives need diamond and a light hand; our guide to sharpening a ceramic knife covers grit and Kyocera's own limits.
The 7 best diamond sharpening stones
SHARPAL 162N Diamond Plate (8 x 3 in)
The plate most people should buy. It's the full 8 by 3 inch bench size, which gives a chef's knife room to sweep, with 325 for repairs and 1200 for a working edge. SHARPAL electroplates monocrystalline diamond onto a steel base about a third of an inch thick and says to use it dry. The case turns into a non-slip base, and the clip-on angle guide covers 14 to 25 degrees, so a beginner has something to lean on. With 4,000+ ratings and 1,000+ purchases a month, it has more owners than any other plate here.
- Size8 x 3 in
- Grits325 (45 micron) / 1200 (12 micron)
- Diamondmonocrystalline, electroplated on 0.35 in stainless
- Usedry
- Extrasstorage box doubles as non-slip base, angle guide (14, 17, 20, 25°)
- Warranty3 years
Why it stands out
- Bench size for long knives and tools
- Case doubles as a non-slip base
- Angle guide included
Think twice if
- You want a finer finish than 12 micron without a second stone
- You need a pocket-size plate
DMT FWFC Diafold (fine/coarse)
DMT has been making diamond sharpeners for more than 50 years, per the listing, and this folding version is the one people throw in a toolbox or tackle bag. The handles fold over to protect the plate. It pairs DMT's coarse (45 micron) with its fine (25 micron), so it's a working-edge tool rather than a polisher: sharpen here, then finish on a strop or fine ceramic. DMT's polka-dot pattern catches steel dust in the recessed dots. DMT's whole lineup, from credit cards to the Dia-Flat, is sorted by job in our DMT diamond sharpener review.
- Gritscoarse 45 micron (325 mesh) / fine 25 micron (600 mesh)
- Size9.5 in open, 5 in closed
- Diamondmicronized monocrystalline
- Usedry or with water
Why it stands out
- Folds closed to protect the diamond
- Made in USA, dry or with water
- Light enough for a pack
Think twice if
- You want a big bench plate for 10-inch kitchen knives
- You want an extra-fine side
Ultra Sharp 3-Stone Diamond Set
Three full-size plates (300, 600 and 1200) and a holder, for people who sharpen everything from axes to pocket knives. Ultra Sharp's listing says they handle ceramic knives too, and the lifetime warranty covers you if the coating wears. Each stone weighs 2.2 pounds, so they sit still on the bench. It costs more up front, but you get the coarse-to-fine progression that single plates force you to split across two purchases.
- Stones3, each 8 x 3 in
- Grits300 / 600 / 1200
- Holderfits stones 6 to 9 in
- Weight2.2 lb per stone
- Warrantylifetime
Why it stands out
- Full three-step progression
- Heavy, stable 8 x 3 inch plates
- Lifetime warranty
Think twice if
- You sharpen a few kitchen knives and don't need three plates
Atoma #400 Diamond Plate
The plate Japanese-stone users buy to keep their stones flat. Sharpen-Up's roundup recommends the #400 mainly for flattening water stones and warns that, used carelessly, a plate this coarse can damage a knife. Owners on Kitchen Knife Forums describe Atomas as harsh-feeling with deep scratches. That's exactly what makes it good at flattening and repairs, and why it's the wrong plate to finish an edge on.
- Grit#400 (medium rough)
- Size8 x 2.77 x 0.32 in
- Typediamond
Why it stands out
- Fast, flat lapping for water stones
- Quick repairs on chipped edges
Think twice if
- You want one plate to sharpen and finish knives
- The listing is short on detail (grit and size only)
Open the Atoma listing to see the plate's diamond pattern close up
Naniwa Diamond Whetstone #1000
A thick diamond whetstone rather than a thin plate, from one of Japan's best-known stone makers, and it showed 1,000+ purchases in the past month in our search. Naniwa's listing is thin, giving only the grit and size, so we can't tell you the bond type from it. Owners on Kitchen Knife Forums describe Naniwa diamond stones as slower than plates but nicer to use, with a better finish. Pick it if you sharpen Japanese kitchen knives and want diamond speed on hard steel without the scratchy plate feel.
- Grit#1000
- Size210 x 75 x 16 mm (8.3 x 2.95 x 0.62 in)
- ModelDR-7510
Why it stands out
- Stone-like format at #1000
- Strong recent sales
Think twice if
- You want full specs on the listing before you buy
- Budget matters (it costs several times a SHARPAL plate)
Smith's DCS4 4-inch Diamond Combination
For the truck, the boat or a hunting pack. The stone stores inside its own handle, each side has a groove for fish hooks and pointed tools, and the interrupted surface collects filings as you go. Four inches is too short for kitchen work, but it will bring a dull pocket or hunting knife back in a few minutes. It has 3,400+ ratings.
- Size4 in stone in a rubber-grip handle
- Gritscoarse and fine (color coded)
- Surfaceinterrupted, monocrystalline diamond
- Extrasfish-hook groove, micro-tool pad, lanyard loop
Why it stands out
- Stores in its own handle
- Hook groove and micro-tool pad
Think twice if
- You sharpen long kitchen knives
DMT Dia-Sharp Credit Card Set (3)
Three credit-card plates, coarse to extra-fine, each in a color-coded sleeve. They're a continuous-surface DiaSharp, which DMT recommends for small pointed tools that could catch in a dotted plate. Lay one flat on a table or hold it and stroke the knife across. They won't replace a bench plate, but they cover the full 45 to 9 micron range in a wallet.
- Stones3, each 3.25 x 2 x 0.05 in
- Gritscoarse 45 micron, fine 25 micron, extra-fine 9 micron
- Surfacecontinuous Dia-Sharp
- Usedry or water
Why it stands out
- Full three-grit range, pocket size
- Continuous surface for small points
Think twice if
- Your main knives are kitchen knives over 6 inches
Also good: the SHARPAL 156N is the 6 by 2.5 inch version of our top pick, with the same 325/1200 grits, for smaller benches. For flattening only, the SCOTTCHEN 10 x 3 inch lapping plate pairs 120 and 180 grit. Our best flattening stone guide compares it with the other plates made for flattening.
Side-by-side comparison
| Stone | Size | Grits | Best for |
|---|---|---|---|
| SHARPAL 162N | 8 x 3 in | 325 / 1200 | Knives and tools, one plate |
| DMT Diafold FWFC | Folding | 45 / 25 micron | Toolbox, tackle box |
| Ultra Sharp set | 3 x (8 x 3 in) | 300 / 600 / 1200 | Sharpening everything |
| Atoma #400 | 8 x 2.77 in | 400 | Flattening, repairs |
| Naniwa #1000 | 210 x 75 mm | 1000 | Japanese kitchen knives |
| Smith's DCS4 | 4 in | Coarse / fine | Pocket and field |
| DMT credit cards | 3.25 x 2 in | 45 / 25 / 9 micron | Wallet, travel |
What to look for in a diamond plate
Monocrystalline diamond. Both DMT and SHARPAL use it. Sharpen-Up's guide notes that single-crystal diamonds last longer than polycrystalline ones, which fracture into smaller pieces as they wear.
Continuous or interrupted surface. A dotted or "interrupted" surface gives steel dust somewhere to go, so it cuts fast and stays clean. DMT recommends a continuous surface for small points and tools that might catch in the holes.
Plate, resin stone or vitrified stone. Most products here are electroplated plates: one layer of diamond on steel. They're fast and flat, and scratchy to use. Resin-bond and vitrified diamond stones (Naniwa's and many Japanese makers') bury the diamond in a binder that wears slowly like a normal stone. Kitchen Knife Forums owners call them nicer to use and more expensive.
Size. Eight by three inches for kitchen knives up to about 10 inches. Six inches is fine for pocket and hunting knives. Four inches and under is for the field.
How to use a diamond stone
- Set the plate on a non-slip base or damp towel. Dry is fine; a splash of water keeps the steel dust moving. DMT says oil won't damage its plates but can slow them if you use too much.
- Use light pressure. DMT's FAQ is blunt about it: the diamonds do the cutting, so you don't need to press. Heavy pressure only wears the coating faster.
- Hold your angle and stroke edge-first, heel to tip, until you can feel a burr along the whole opposite side. The marker trick shows whether you're hitting the edge.
- Flip, raise the burr back, then repeat on the finer side with lighter strokes.
- Finish off the plate. Diamond leaves a toothy edge; Knivesandtools recommends a leather strop to polish it, and our how to strop a knife guide covers that step.
- Rinse and wipe the plate dry. Every few sessions, DMT suggests a mild kitchen cleanser and a nylon brush.
Expect the coarse side to feel aggressive for the first few sessions. DMT calls that the break-in period; the surface smooths out without losing its long-term cut, so go gently on good knives until it settles.
If you only buy one thing: the SHARPAL 162N, and a strop to finish on.
Grit sizes and care guidance from DMT's published FAQ, plus DMT's D8ME product page for the 6 micron grade; buying notes from Sharpen-Up's diamond stone guide, Knivesandtools' diamond stone guide and the Kitchen Knife Forums "diamond stone survey" thread, read October 13, 2026. Specs and sales figures from Amazon listings checked the same day. How we research · Affiliate disclosure