Diamond Core Drill Bits – Hollow Core Bits for Stone, Glass & Ceramic

Professional diamond core drill bits for drilling clean, precise holes in stone, glass, ceramic tile, granite, marble, and gemstone materials. The hollow core design removes a cylindrical plug — producing smooth, chip-free holes with minimal heat buildup. Available from 1mm to 150mm diameter for lapidary, jewelry, and construction applications.

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Core Bit Specifications

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Frequently Asked Questions

• Q: What is a core drill bit used for?
  A: A core drill bit drills a hollow cylindrical hole, removing a solid plug of material. This produces a clean, precise hole with less heat and friction than a solid drill bit — ideal for stone, glass, ceramic, and gemstone drilling.
• Q: Do diamond core bits require water cooling?
  A: Yes — water cooling is essential for diamond core bits. It prevents overheating, flushes debris from the hole, and dramatically extends bit life. Use a water feed attachment or drill in a water-filled container for small bits.
• Q: What drill speed should I use for core drilling stone?
  A: Lower RPM is better for larger diameter bits. A general guide: 1–6mm bits at 3,000–6,000 RPM; 6–25mm at 1,000–3,000 RPM; 25mm+ at 300–1,000 RPM. Always use light, consistent pressure with coolant running.