General information for trade users. Always follow the manufacturer's instructions for your blade and machine, and use the right personal protective equipment. Last reviewed: 30 September 2026. We'll be adding more cutting tips and techniques to this guide over time.
What is a diamond blade made of?
A diamond blade has four parts: the diamond grit (synthetic diamond crystals), a metal bonding matrix that holds them, the segments formed from that mix, and a slotted steel core. The metal bond is a blend of metal powders (cobalt, iron, nickel, tungsten and bronze are typical) chosen so it wears at a controlled rate, holds the diamonds without pulling them out, and acts as a heat sink. The segments are slightly wider than the steel core so the blade doesn't bind in the cut, and the slots (gullets) between them let air or water flow through for cooling.
How do diamond blades actually cut?
They don't cut like a knife — they grind. Exposed diamond crystals on the edge and sides of the segment score the material into a fine powder. As they grind, the diamonds fracture into smaller pieces and the metal bond wears away too, which exposes fresh diamonds at the surface. That constant cycle of grinding and wearing is what keeps the blade cutting until it's worn out. The blade and the material have to work together: the diamond grit and the bond must both be matched to the material and the machine, or the blade won't perform.
How do I choose the right diamond blade?
Price versus cost per cut. For small or occasional jobs, an economical blade is usually fine. For big jobs or regular use, a premium blade gives a lower cost per cut even though it costs more up front.
The machine. Match the blade to the saw or grinder — its power and speed. Blades are designed to run at specific speeds, and every blade diameter has a maximum safe speed that must never be exceeded. Typical cutting depths by diameter: 100mm blade ≈ 25mm deep, 115mm ≈ 30mm, 125mm ≈ 40mm, 230mm ≈ 83mm, 300mm ≈ 100mm, 350mm ≈ 117mm, 400mm ≈ 143mm, 450mm ≈ 168mm, 500mm ≈ 194mm, 600mm ≈ 244mm. Actual depth varies with the saw, blade flanges and guards.
The material — the most important factor. The rule of thumb: hard materials need a soft bond; soft or abrasive materials need a hard bond. A soft bond releases worn diamonds quickly so new grit stays exposed when cutting hard materials like granite or engineering brick. A hard bond holds diamonds longer when cutting soft, abrasive materials like asphalt or lightweight block. Cutting a soft, abrasive material with a soft bond loses good diamonds before they're used up, and the blade will cut but wear out fast.
Wet or dry. Wet blades must be used with water. Dry blades can be used either way as the equipment and job allow. Electric hand tools shouldn't be used with water for safety reasons; floor saws usually prefer wet cutting for deeper cuts; petrol hand saws often run dry blades with water used as dust control.
What affects cutting speed and blade life?
- Softer bond — faster cutting, shorter life. Harder bond — slower, longer life.
- Higher diamond quality — faster and longer lasting.
- Coarser grit — faster cutting, longer life in soft materials. Finer grit suits dense materials like marble and tiles, and finer grit at higher concentration in a soft bond gives longer life in hard materials.
- Higher horsepower — faster cutting, shorter blade life.
- Shallow cuts — faster and kinder to the blade than deep cuts.
- Large aggregate and heavy steel reinforcement — slower cutting and shorter life.
- Good water flow (wet cutting) — slower cutting but longer blade life, because slurry is flushed from the cut.
What should I know about the material I'm cutting?
Green concrete (under roughly 48 hours old) is very abrasive because the sand isn't fully bonded to the mortar yet. It needs a blade with undercut protection to stop the steel core wearing at the segment weld. Cured concrete is fully hardened, and its compressive strength and aggregate drive the choice: very hard concrete (8,000+ PSI, e.g. nuclear plants) down to soft (3,000 PSI or less, e.g. pavements and patios).
Aggregate makes up 60–75% of concrete volume and matters a lot. Hard aggregates (flint, sea or river gravel, quartz — Mohs 6–9) dull diamonds quickly and need a softer bond; soft limestone needs a harder bond. Large aggregate cuts slower than small. Sharp (crushed or bank) sand is more abrasive than round river sand. Steel reinforcement slows cutting and shortens blade life noticeably — around 1% steel can cut blade life by roughly a quarter, and 3% by up to three quarters.
Asphalt is highly abrasive and cut almost immediately after laying. Use a bond similar to green concrete, with undercut protection, and avoid cutting through into the abrasive sub-base below. Brick and block: concrete block tends to be soft and abrasive, brick harder and less so. Stone ranges from hard flint, granite and slate to soft limestone. Tile is hard at the upper end, and porcelain — vitrified at extreme firing temperatures — is one of the hardest materials commonly cut. To limit chipping, blades with continuous rims, closely spaced segments or turbo segments are popular for tile work.
Dry cutting safety
Do: match the blade's direction arrow to the machine's rotation; wear eye, face, head, hearing and hand protection; keep the machine guard fitted; secure the material; enter the cut straight without tilting; use a gentle back-and-forth pendulum motion to disperse heat; let the machine's own weight do the work.
Don't: make long continuous cuts or cut too deep in one pass with a dry blade; force the blade through the cut; cut curves; use a cutting blade for grinding or raking out mortar; cut metal, wood or unsuitable materials; let the cutting edge overheat.
Wet cutting safety
Do: supply water to both sides of the blade; cut parallel to the wheel axis; follow the manufacturer's pulley size and speed for the blade diameter; keep drive belts tight; use the drive pin if fitted; keep the guard in place and secure. Don't: force the blade or mount it on an undersize spindle; pack out clamp plates with paper washers; force the blade into the material; run with a damaged or open guard.
Wet diamond core drilling tips
Set the drill rig rigidly and level so the bit can't bind, with proper clearances on the core bit, constant water flow and the right speed and power. Lower the bit into the cut slowly with no skidding, apply steady pressure without forcing it, and never stop the water or the rotation while the bit is in the hole. When the bit hits rebar, ease off about a third and let it cut at its own rate. If penetration slows, the segments may be glazed and need redressing — a common fix is to briefly reduce the water flow and let masonry sand enter the hole, or dress the bit on a soft block, then return the water to normal. When finished, back the bit out of the hole with the motor running and the water turned down low.
Dry diamond core drilling tips
Dry cores give fast, clean service entries in brick and internal wall materials, popular with electricians, plumbers, heating engineers and fitters. Use an 850W-plus rotary drill with clutch and variable speed — and no hammer action. Pilot the wall first with a 13mm masonry bit, keep the chuck tight, and use a slotted core unless you're running dust extraction (unslotted cores need extraction; without it they overheat, lose segment life and can jam). Run slower for harder materials and larger diameters, faster for softer materials and smaller cores — higher speed doesn't always mean better penetration. Clear swarf regularly, rotate the bit in and out of the hole, keep the machine level, and reduce pressure if the bit starts to vibrate.
Why is my blade not cutting properly?
Blade stops cutting (glazed segments): usually a bond too hard for the material, or excessive pressure, leaving no fresh diamond exposed. The blade needs redressing, and a softer bond will suit better next time.
Cracked core or segments / loss of tension: typically excessive pressure or a bond too hard for the material, making the blade pound in the cut. Check the machine's RPM, shaft and flanges for wear, and service it regularly.
Rapid wear: usually a bond too soft for the material, releasing diamonds early. In wet cutting, too little water leaves abrasive slurry in the cut — increase the flow. A blade wearing out of round points to worn bearings or shaft.
Overheating: look for black or bluish discolouration on the steel core. Caused by a bond too hard for the material or excessive pressure — let the blade do the work and use that pendulum motion on hand-held saws.
Segment loss: often a bond too hard for the material, twisting in loose material, or undercutting from cutting into an abrasive sub-base. Look for blades with core protection such as drop segments, and avoid cutting below the surface material.
Uneven segment wear: in wet cutting this usually means blocked or uneven water on one side; out-of-round wear points to a damaged bearing or shaft. On floor and bench saws, check wheel and carriage alignment.
Find the right blade
Our Abrasives & Blades range covers diamond blades and cup grinders, and our Drill Bits & Cores range includes wet and dry diamond core bits and accessories. For more practical trade advice, see the Trade Guides hub.