"Diamond drilling" describes the tool. "Core drilling" describes the output. On a typical concrete job they refer to the same activity. Once you see why, the rest of the terminology slots into place.
Diamond drilling — the tool
"Diamond" refers to the synthetic-diamond segments brazed onto the cutting edge of the drill. Diamond is one of the few materials hard enough to cut through reinforced concrete, brick, granite and similar substrates. The technique covers anything from a 12 mm anchor hole to a 1000 mm Ø service riser.
Calling it "diamond drilling" emphasises how the cut is made — by abrasion, with diamond — rather than the shape of the result.
Core drilling — the output
"Core" describes the cylindrical plug that comes out of the hole. A diamond drill bit is hollow — it grinds a circular slot through the substrate and lifts the resulting cylinder (the "core") out as it withdraws. So when someone says "we need a 200 mm core through the slab", they're talking about the same thing as a 200 mm diamond drill — described from the result's point of view.
Diamond drilling is what we do. Core drilling is what comes out the other side.
So when do they mean different things?
Two contexts where "diamond drilling" is broader than "core drilling":
- Solid bits. Diamond bits below about 25 mm Ø are usually solid (no hollow centre, no core extracted). Anchor bolts, sleeves, tie-rod holes — diamond drilled, not core drilled. Used for fixings, balustrade rods, etc.
- Sampling cores. "Core drilling" is also the term in geotech and structural surveying for taking samples of a slab or rock to test composition. Same equipment, different purpose. We do these too.
And one context where "core drilling" is broader than "diamond drilling":
- Wood and metal coring. "Core drilling" is also a term used for hole saws cutting cylinders out of wood or sheet metal. Different industry, different kit. Not what we do.
Which term to use when you brief a contractor
For most concrete and masonry jobs in construction, either term will land. Specs commonly say "core drilling" because it describes the deliverable; trade language often says "diamond drilling" because that's the method. We use both interchangeably and so do most reputable contractors.
What actually matters in a brief:
- Hole diameter (mm Ø)
- Substrate (concrete, reinforced concrete, brick, stone)
- Depth or thickness
- How many holes
- Position drawing or sketch
- Access & working hours
If you've got those, the terminology takes care of itself.
Related techniques
For full-thickness cuts (not holes), see concrete cutting — wall, floor, wire and hand sawing. For openings too thick or constrained for sawing, stitch drilling uses a row of overlapping cores to break out the shape. For full service info, diamond drilling and core drilling have dedicated pages.
Got a hole to drill? Send the brief → · or read how diamond drilling compares to percussion.