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DMT FWFC DuoSharp Double-Sided Diamond Sharpening Stone

By DMT · Knife Sharpening · Kitchen & Cooking · More from DMT

  • 9.5" open, 5" closed
  • Fine 25 micron/600 mesh
  • Coarse 45 micron/325 mesh
  • 4.33" x 0.88" x 0.25"
  • Folding plastic handles

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Summary

A folding two-sided diamond sharpener with a coarse side and a fine side, small enough for a pocket, toolbox or kitchen drawer. Check which grit pair you need before buying: the coarse side is aggressive, and the Fine/Extra-Fine version suits plain maintenance better.

Strengths

  • Cuts fast on common knife steels, including 154-CM, S30V, S35VN and VG-10.
  • Folds to 5 in and slips into a pocket, toolbox or kitchen drawer.
  • The diamond surface needs no oil, no soaking and no flattening.
  • Two grits cover both damaged edges and routine touch-ups.
  • Owners on BladeForums and Rokslide report years of use on all steels, including S90.
  • DMT’s defect warranty replaces faulty units free of charge.

Weaknesses

  • Cannot sharpen serrations or recurves.
  • The 0.88 in stone is narrow and awkward on large blades.
  • The coarse side is aggressive; some users find the Fine/Extra-Fine pair a better fit.
  • The plastic clam-shell packaging is hard to open.
  • No independent instrumented test of this model exists.
  • The diamond surface wears over time and is not replaceable.

Verified specifications

ModelFWFC, Double Sided Diafold Sharpener, Fine/Coarse.
Gritscoarse 45 micron (325 mesh) and fine 25 micron (600 mesh).
Stone dimensions4.33 × 0.88 × 0.25 in (110 × 22 × 6 mm).
Open length9.5 in (241 mm).
Closed length5 in (127 mm).
Diamondmonocrystalline, micronized.
Surfaceinterrupted pattern, with a continuous zone for small or pointed edges.
Lubricationnone needed; use dry or with water.
Handlesfolding plastic that enclose and protect the stone when closed.
Country of manufacturethe sharpener plate is made in the USA; other components are made in China.
Color codingcoarse side blue, fine side red.
Weightnot published.
In the boxthe sharpener only; instructions are printed on the packaging.
Full research notes and sources

Coarse and fine sides

The FWFC puts two grits on one 4.33 × 0.88 × 0.25 in plate. The coarse side is 45 micron (325 mesh) for dull or damaged edges; the fine side is 25 micron (600 mesh) for maintenance. The coarse side uses an interrupted pattern and the fine side keeps a continuous zone for pointed edges. It works dry or with water, needs no oil and never needs flattening, which is the practical edge over a waterstone. The stone is narrow, though, so large blades and recurves are awkward, and the tool cannot sharpen serrations at all. If you only touch up already-keen edges, one owner switched to the Fine/Extra-Fine variant after finding the coarse side too aggressive.

A 2017 BladeReviews.com review used it for several months and reported it could bring most folding knives back to a hair-shaving edge in steels like 154-CM, S35VN, S30V and VG-10, while noting it cannot handle recurves or serrations. The same reviewer paid about $25 at the time and called DMT the gold standard in diamond sharpeners. Forum feedback is consistent: a BladeForums member reported owning three Diafolds, and a 2024 Rokslide poster called it light and effective on all steels, including S90, with a handle that keeps your hand away from the blade. Highland Woodworking’s review of DMT’s larger Dia-Sharp bench stones, a different line, praised the monocrystalline diamond’s speed and resistance to dishing. No major outlet has run an instrumented test; Wirecutter’s knife sharpener guide covers electric sharpeners only.

Wear, care and warranty

DMT’s warranty is its “Commitment”: products are guaranteed free of defects in materials and workmanship, and confirmed defects are replaced free of charge. Normal diamond wear is not covered. DMT says that with proper care, kept clean and stored dry, its sharpeners last a long time, and some customers report twenty years of service. There are no user-serviceable parts; when the diamond surface wears out, the tool is done. Cleaning a clogged diamond stone is the only maintenance.

Is it worth it?

DMT lists the FWFC at $51.99, a premium over generic diamond stones that buys a long market history and a US-made plate. For comparison, KnifeWorks lists a related Diafold in Fine/Extra-Fine at $39.99 on sale, and the reviewer at BladeReviews paid about $25 back in 2017, so the price has climbed over the years. There are no consumables beyond an occasional cleaning. If you want a guided system instead, DMT’s Magna-Guide is sold separately at $67.99.

Which model this is

This page covers the FWFC, the Fine/Coarse Diafold.

The Amazon listing is ASIN B00004WFTW.

DMT also sells the Diafold in Coarse/Extra-Coarse (FWCX), Extra-Fine/Fine (FWEF) and Extra-Fine/Extra-Extra-Fine (FWEEE). The larger 8 in and 10 in DuoSharp bench stones are a different product line.

Sources

Manufacturer:

Independent reviews:

Owner reports:

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