Gear guide
Best Whetstone Flattening Stones and Diamond Lapping Plates
Picked from Amazon listings, not hands-on tests. How we pick
A water stone wears hollow with use, and a dished stone cannot give an even edge from heel to tip. The fix is to draw a pencil grid on the face and rub it on something flat until the grid is gone. Two tools are sold for that. A whetstone flattening stone is a block of coarse silicon carbide, usually grooved so the slurry has somewhere to go; it wears as it works, so its own face needs checking. A diamond lapping plate is a metal plate coated with diamond, and a diamond plate stays flat. The listings differ in type, in grit (a coarse side for coarse stones, a finer side for finishing stones), in size against the stone you own, and in whether the face is grooved. This guide compares seven sharpening stone flatteners by what their Amazon listings state. Nothing here was tested.
Compare the picks
| Pick | Type | Grit | Size | Surface | Price | Link |
|---|---|---|---|---|---|---|
 SHARPAL 145H diamond lapping plate, 10 x 4 in | Diamond lapping plate | 220 (60 micron) | 10 x 4 in | not stated | - | Amazon |
 Sharp Pebble flattening stone, 120/320 grit | Silicon carbide stone | 120/320 | 7.99 x 2.79 in | Diamond-pattern grooves | - | Amazon |
 POWERTEC 72124 flattening stone, 120/320 grit | Silicon carbide stone | 120/320 | 8 x 3 x 1-3/16 in | Diamond-shaped grooves | - | Amazon |
 DMT Dia-Flat diamond lapping plate, 4 x 10 in | Diamond lapping plate | 160 mesh (95 micron) | 10 x 4 in | not stated | - | Amazon |
 SCOTTCHEN diamond flattening plate, 120/180 grit | Diamond plate, two-sided | 120/180 | 10 x 2-11/16 x 3/8 in | not stated | - | Amazon |
 Angerstone flattening stone set, 150 and 320 grit | Flattening stones, set of 2 | 150 and 320 | not stated | Grooved | - | Amazon |
 Shun leveling stone for whetstones | Leveling stone | not stated | not stated | Grooved, ridged side | - | Amazon |
Facts are taken from each Amazon listing. Prices are checked daily and shown with their date.
If you just want one
- Closest match for the jobSHARPAL 145H diamond lapping plate, 10 x 4 inFlatness is stated: precision ground to plus or minus 0.002 inch (0.05 mm).
- Most for the money on paperSCOTTCHEN diamond flattening plate, 120/180 gritTwo diamond sides, 120 and 180 grit, on a plate 10 inches long and 2-11/16 inches wide.
- Most complete listingSharp Pebble flattening stone, 120/320 gritDual grit: 120 for coarse water stones (900 grit and below) and 320 for fine stones (1000 grit and up), as the listing puts it.
The picks in detail
Pick 1 · SHARPAL
SHARPAL 145H diamond lapping plate, 10 x 4 in
See price on AmazonA 10 by 4 inch diamond lapping plate in extra coarse 220 grit (60 micron) monocrystalline diamond, ground flat to within 0.002 inch. It has an anti-slip rubber base and is listed for natural and synthetic stones.
What the listing offers
- Flatness is stated: precision ground to plus or minus 0.002 inch (0.05 mm).
- Extra coarse 220 grit (60 micron) monocrystalline diamond, listed for natural and synthetic stones.
- An anti-slip rubber base is included, and the 10 by 4 inch plate takes larger whetstones.
Limits to know
- A single grit: there is no finer side for a last pass on polishing stones.
- The listing does not say whether the diamond face is continuous or grooved.
Pick 2 · Sharp Pebble
Sharp Pebble flattening stone, 120/320 grit
See price on AmazonA two-sided black silicon carbide flattening stone, 7.99 by 2.79 inches. The listing assigns the 120 grit side to stones of 900 grit and below and the 320 side to stones of 1000 grit and up.
What the listing offers
- Dual grit: 120 for coarse water stones (900 grit and below) and 320 for fine stones (1000 grit and up), as the listing puts it.
- The flattening area is 7.99 by 2.79 inches, sized by the listing for a full-size whetstone.
- A diamond-shaped groove pattern channels slurry and waste away while it cuts.
Limits to know
- Silicon carbide wears as it works, so the flattener itself needs checking for flatness over time.
- The listing does not state the thickness of the stone, and no base or holder is mentioned.
Pick 3 · POWERTEC
POWERTEC 72124 flattening stone, 120/320 grit
See price on AmazonA large dual-grit silicon carbide flattening stone at 8 by 3 by 1-3/16 inches, with a coarse 120 side and a fine 320 side. The 3 inch width gives room for wide bench stones.
What the listing offers
- Coarse 120 grit and fine 320 grit sides, listed for whetstones, oil stones and water stones.
- All three dimensions are stated: 8 inches long, 3 inches wide and 1-3/16 inches thick.
- A diamond-shaped grid of grooves removes waste material during flattening; it is used with water.
Limits to know
- The listing does not say which side to use on which whetstone grits.
- Like any silicon carbide flattener it wears as it works, so its own face needs checking from time to time.
Pick 4 · DMT (Diamond Machining Technology)
DMT Dia-Flat diamond lapping plate, 4 x 10 in
See price on AmazonDMT's 10 by 4 inch lapping plate for flattening conventional stones and water stones, with a 95 micron (160 mesh) diamond surface and a hardcoat coating. Made in the USA.
What the listing offers
- A 10 by 4 inch plate sold specifically for flattening conventional stones and water stones.
- The 95 micron (160 mesh) diamond surface is listed for water stones, oil stones and Arkansas stones.
- Uses DMT's Diamond Hardcoat coating and is made in the USA, according to the listing.
Limits to know
- One coarse surface only (95 micron), with no finer side.
- No flatness tolerance and no thickness or weight are stated in the listing.
Pick 5 · SCOTTCHEN
SCOTTCHEN diamond flattening plate, 120/180 grit
See price on AmazonA double-sided diamond flattening plate, 10 by 2-11/16 by 3/8 inches, with 120 grit on one side and 180 on the other. Materials are given as diamond, steel and ABS, and it can be used dry or wet.
What the listing offers
- Two diamond sides, 120 and 180 grit, on a plate 10 inches long and 2-11/16 inches wide.
- Can be used dry or wet, according to the listing; materials are given as diamond, steel and ABS.
- Listed for flattening whetstones, oil stones and water stones, and for re-beveling axes and other tools.
Limits to know
- The listing warns to dry it after wet use to prevent rust.
- Both sides are coarse (120 and 180), and no flatness tolerance is stated.
Pick 6 · Angerstone
Angerstone flattening stone set, 150 and 320 grit
See price on AmazonTwo separate flattening stones: a black 150 grit stone to level the whetstone and a white 320 grit stone to remove the scratches afterwards. The coarse surface is silicon carbide; no sizes are given.
What the listing offers
- Two stones in the set: 150 grit (black) for flattening first and 320 grit (white) for removing scratches and iron filings.
- The coarse surface is silicon carbide, and the title describes the stones as grooved.
- Listed for re-leveling whetstones, oil stones, water stones and ceramic stones.
Limits to know
- No dimensions are stated, so the stones cannot be compared with the length of your whetstone.
- The material of the white 320 grit stone is not stated in the listing.
Pick 7 · Shun
Shun leveling stone for whetstones
See price on AmazonA grooved leveling stone sold under the Shun knife brand. Both stones are soaked in water, then the ridged side is rubbed over the whetstone. The listing states no grit, size or material.
What the listing offers
- Grooves are designed to collect the material removed from the whetstone.
- The listing gives the method: soak both stones in water, then rub the ridged side over the uneven surface.
- Sold under the Shun name as the leveling tool for a whetstone.
Limits to know
- The listing states no grit, no dimensions and no abrasive material.
- It needs soaking in water before use, a step a diamond plate does not have.
Read before you buy
- Why Won't My Knife Sharpen on a Whetstone?Knife still dull after 20 minutes on a whetstone? A symptom table with 8 causes and fixes, from an angle that is too low to a burr that never came off.
- Whetstone vs Diamond Stone for Knife SharpeningWhetstone vs diamond stone compared on speed, soaking, flattening, finish and wear, with a first-stone pick by case. Starts at 1000 grit.
- What Grit Whetstone Do You Need?Which whetstone grit to buy: 1000 for one stone, add 3000 to 6000 for two, add 240 to 400 for three. With a table by knife and edge condition.
- How to Flatten a Sharpening Stone: 3 Methods and When to Do ItFlatten a dished whetstone with a pencil grid and one of 3 tools: a flattening stone, a diamond lapping plate or 220 grit wet/dry sandpaper on glass.
- How to Clean a Sharpening Stone (Water, Oil, Ceramic, Diamond)Clean a grey, glazed sharpening stone by type: water, oil, diamond or ceramic. What to use, what never to use, and the sign that the stone needs flattening.
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Stone and Strop chooses every product independently from what its Amazon listing states. We may earn a commission from the links above. As an Amazon Associate I earn from qualifying purchases.