How To Use Diamond Sharpening Stone | A Master Bladesmith’s Method

Diamond stones cut faster than oil stones and never need soaking, which is why they’ve become the go-to for kitchen knives, pocket knives, and garden tools alike. But speed cuts both ways: too much pressure removes more metal than you want and shortens the stone’s life. Sharpen with a light, steady hand and you’ll get a razor edge in minutes.

Set Up Your Stone And Blade

Place the diamond stone on a stable, flat surface so it won’t slide mid-stroke. If your model has a non-slip rubber base or mat, that’s exactly what it’s for — use it.

You’re aiming for a consistent sharpening angle, usually around 20 degrees, held the same way on every pass. “Consistent” matters more than “perfect”; a slightly steep angle held steadily beats a perfect angle that wanders.

For your very first time, try a Sharpal 4-sided model or a DMT dia-sharp. If you’re comparing options, our tested roundup of the best diamond sharpening stones breaks down which ones hold up for years of garden tool work.

Which Grit Should You Start With?

Start with the grit that matches your blade’s condition, not the finest one you own. DMT’s manual recommends extra-coarse only for badly damaged edges, coarse for neglected ones, and finer grits for routine touch-ups.

If you only have two grits, use the coarser one first, then the finer one.

Diamond stones remove metal faster than conventional stones, so don’t over-sharpen. Once a burr forms, you’re done with that grit.

Sharpening Strokes That Work

Push the blade away from you along the stone on one side, then flip it and pull toward you on the other, keeping the same angle. Smith’s instructions describe exactly this motion: push on one side, pull on the other, maintaining the same approximate angle throughout.

Alternating sides each pass keeps the edge centered. Or fully sharpen one side before switching — Sharpal says either works, as long as your angle and stroke stay consistent. Use light pressure; the diamond surface does the work, and pressing hard just wears out the stone faster.

You’ll know you’re done with a grit when a small burr, a rough lip, forms along the edge on the opposite side. That’s your cue to flip and repeat, then move to the next finer grit and repeat until the burr disappears.

Clean Up And Keep It Cutting

After sharpening, wipe the stone with a dry paper towel to remove loose filings. For embedded metal dust, work a rubber eraser or a nylon brush across the surface — Sharpal’s manual suggests both.

Diamond stones work dry or with a few drops of water. Smith’s instructions say you can use water or a non-petroleum honing solution, but never petroleum-based oils, which can gum up the diamond surface. After each session, wash the stone and dry it before storing.

Keep the stone flat on your bench as you work, and keep your fingers clear of the edge. Diamond stones cut aggressively, so a slip is more than a nick.