How to Choose a Diamond Core Drill Bit for Tile and Stone

Cutting a clean hole in porcelain or granite starts with the right bit. Match size, arbor, and cooling method to the job before you buy.

Match the diameter to your fixture

Measure the pipe, cable, or fitting first. A faucet stem or a sink drain each needs a specific opening. A fixed size like a 32mm diamond core bit suits common faucet and sink work, so confirm the number before ordering.

Check the arbor and machine fit

Diamond core bits often use a 5/8-11 thread. That fits many angle grinders and wet polishers. A hex adapter lets the same bit run in a drill, so read the mount before you assume compatibility.

Decide dry or wet cutting

Many bits work both ways. Water clears dust, keeps the grit cool, and can extend life on glass and dense stone. Dry cutting is faster to set up but generates more debris.

Respect the material limits

Read the rated surfaces closely. A bit rated for non-reinforced concrete will struggle in rebar. Never switch to hammer mode when the maker forbids it, as percussion can strip the diamond bond.

Plan your entry angle

Start at a slight tilt to score a ring, then bring the bit upright. This stops skating on smooth glaze and keeps the hole centered on your mark.

The bottom line

Pick by diameter, arbor, and cooling method, then honor the material and mode limits. A well-matched core bit gives clean holes and a longer working life.