The Complete Guide to Using Core Drill Bits on Granite and Marble

Sep. 10, 2025

Drilling into granite or marble requires specialized tools and techniques to ensure clean, precise holes without damaging the stone. Stone core drill bits are specifically designed for these tasks. In this guide, we cover how to use core drill bits on granite, available sizes, wet vs dry drilling methods, and recommendations for the best bits for granite and marble.

How to Use a Core Drill Bit on Granite

Using a core drill bit correctly is essential for a smooth and precise hole:

Mark Your Drilling Spot – Clearly mark the area where the hole is needed. Use tape or a template to prevent the bit from slipping.
Secure the Granite – Clamp the stone or use a stable surface to avoid movement during drilling.
Choose the Drilling Method – Decide whether you will use wet or dry drilling depending on the bit type and material hardness.
Start Slowly – Begin drilling at a low speed to establish a guide hole and reduce chipping.
Apply Steady Pressure – Do not force the drill. Let the bit do the cutting naturally.
Cool the Bit if Needed – For wet drilling, maintain a continuous flow of water to keep the bit cool and reduce dust.

Following these steps ensures precise, clean holes while protecting both the drill bit and the granite.

Stone Drill Bit Sizes for Granite and Marble

Stone core drill bits come in a variety of sizes to suit different applications:

Small Bits (6–20mm) – Perfect for tiles, decorative stone, or plumbing holes.
Medium Bits (25–100mm) – Ideal for countertop installations, electrical work, and small-scale projects.
Large Bits (100–300mm) – Used for thick slabs or industrial stone applications.
Extra-Large Bits (300–500mm+) – Suitable for heavy-duty projects such as architectural stone drilling.

Selecting the correct size is crucial for achieving accurate results and reducing stress on the stone and the drill.

Wet vs Dry Core Drilling for Stone

The choice between wet and dry drilling depends on the material, equipment, and project requirements:

Wet Drilling – Uses a constant flow of water to cool the bit and reduce dust. Wet drilling is recommended for hard stones like granite and marble, as it extends the bit’s life and ensures smoother holes.
Dry Drilling – Suitable for softer stones or small projects where water is not available. Dry drilling may generate more dust and cause faster bit wear, so it requires careful monitoring and occasional breaks to prevent overheating.

Both methods are effective if used correctly, but wet drilling is generally preferred for harder stones.

Best Stone Core Drill Bits for Granite and Marble

Choosing high-quality core drill bits ensures efficiency and durability. Recommended options include:

Diamond Core Drill Bits – Ideal for hard granite and marble due to their exceptional cutting strength and long lifespan.
Segmented Core Bits – Provide better cooling and reduce heat buildup, making them suitable for continuous drilling.
Laser-Welded Core Bits – Offer precision and durability, perfect for professional projects.
Electroplated Bits – Best for light-duty work on thinner stone slabs or decorative applications.

Investing in premium bits may cost more initially but saves time and replacement costs in the long run.

Conclusion

Drilling into granite or marble requires careful planning, the right tools, and proper techniques. By understanding how to use a core drill bit, choosing the appropriate size, deciding between wet and dry drilling, and selecting the best bit for your project, you can achieve clean, precise holes with minimal risk of damaging the stone. Proper preparation and quality equipment are the keys to success in any stone drilling project.