RTC Porcelain Pro Diamond Bits — Clean, Fast Holes in the Hardest Tile

Hard porcelain, glass, and granite are where cheap bits wander, chip the face, and burn out after a couple of holes. RTC Porcelain Pro Bits bore through all three with an electroplated diamond edge that grinds a clean, fast, precise hole — and each bit is good for roughly 30–50 holes. Run at low speed with water for cooling and they hold up and cut true.

They attach to any drill chuck. When a bit starts cutting slow, bring it back with the Rockin Red Dressing Stone; for edge refinement after drilling, the Diamond Flap Discs finish the job.

Why Tile Pros Choose It

• Cuts the hard stuff: Porcelain, glass, and granite
• Clean holes: Electroplated diamond bores fast and chip-free
• Real life: Roughly 30–50 holes per bit
• Universal fit: Attaches to any drill chuck
• Precise: Grinds an accurate hole where cheap bits wander
• Dressable: Revive the cut with a dressing stone instead of tossing it

Pro tip: Start at an angle to break the glaze, then bring the bit vertical, and keep water on the cut the whole time — heat is what kills a diamond bit. Ease off pressure as you break through to avoid blowing out the back of the tile.