Collection: Diamond Core Drill Bits

Professional diamond core drill bits for precision drilling of glass, ceramic, stone, and gemstone materials. Available from 0.7mm through 59mm diameter — sintered diamond core drills for maximum durability on hard stone and gem materials, and electroplated core drill bit sets (10pcs) for economical glass and ceramic drilling. The hollow core design allows water cooling at the cutting zone for clean, chip-free holes. Always use with water cooling.

Available Sizes & Pricing

Sintered vs Electroplated Core Drills

Compatible Applications

• Glass drilling — fused glass, stained glass, borosilicate, plate glass
• Ceramic and porcelain tile drilling
• Gemstone drilling — agate, jasper, quartz, turquoise, jade
• Stone drilling — granite, marble, slate
• Lapidary pendant and jewelry stone drilling
• Compatible with drill presses, flex shaft machines, and rotary tools with water feed

Related Tools

• Sintered Diamond Core Drills — Full range of sintered core drills for hard materials
• Diamond Wire Hollow Drill Bits — Micro hollow drills (1–4mm) for bead drilling
• Solid Diamond Drill Bits — Solid electroplated bits for general drilling
• Sintered Diamond Burs — Sintered carving burs for stone and glass
• Water Swivel Adaptors — Water feed adaptors for hollow core drilling

Frequently Asked Questions

• Q: What is the difference between sintered and electroplated diamond core drill bits?
  A: Electroplated core drills have a single layer of diamonds bonded to the surface — once that layer wears through, the bit is finished. They are economical for occasional glass and ceramic drilling. Sintered core drills have diamonds embedded throughout the entire metal matrix — as the surface wears, fresh diamonds are continuously exposed, giving much longer service life. Sintered bits are preferred for hard stone, gem materials, and production drilling.
• Q: What diameter core drill should I choose for pendant drilling?
  A: For standard pendant bails and jump rings, 2.0mm–3.0mm holes are most common. For heavier bail hardware, 3.0mm–5.0mm. For large statement pendants with thick bail wire, 6.0mm–9.0mm. Always drill from both sides of the stone to meet in the middle — this prevents blowout on the exit side.
• Q: How do I use water cooling with core drill bits?
  A: Use a water swivel adaptor mounted on your drill press to feed water through the hollow core during drilling. Alternatively, build a small clay dam around the drilling area on the stone surface and fill with water — the hollow core will draw water down through the bit. For glass drilling, a suction cup water reservoir works well.
• Q: What is the 0.7mm 10pcs set used for?
  A: The 0.7mm micro core drill set ($35, 10pcs) is designed for ultra-fine precision drilling in delicate gemstones, thin glass, and micro-jewelry applications where standard 1.0mm bits are too large. At 0.7mm, these are among the smallest diamond core drills available for lapidary and jewelry work.
• Q: Can I use core drill bits in a handheld drill?
  A: Yes, but a drill press or drill press stand is strongly recommended for consistent perpendicular holes and controlled feed pressure. Handheld drilling makes it difficult to maintain consistent water cooling and can cause the bit to wander, resulting in chipped or cracked holes. For best results, use a drill press with a water swivel adaptor.