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Small Diamond Core Drills


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Quantity Purchased Price
1 - 4 $8.12
5 - 9 $7.24
10 - 24 $5.73
25 + $5.19

Sizes Available: 1.00mm, 1.50mm, 2.00mm, 2.50mm, 3.00mm

Similar to our small diamond drill bits but with a core running through the middle, these small diamond cylindrical core drill bits are hollow, allowing water to circulate inside the core. 

Diamond core drill bits are ideal for beginners and excellent for drilling holes in glass, sea glass, tile, ceramic, glazed pottery, beach pottery, beads, pebbles, slate, petrified wood, optical material, composites and rock. 

Diamond core drill bits are not particularly suited for use on extremely hard glass, flint, porcelain, thick shell, fossilized bone or extremely hard precious or semi-precious stones such as quartz and ruby - please use our small diamond drill bits instead for this purpose as they are more robust and have a larger surface area. 

  • Use on slow speeds. We recommend not exceeding 10,000 rpm
  • Use little pressure. Let the weight of your rotary tool do the work
  • Use with plenty of cold water

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Please read on for usage instructions, chuck and collet requirements and further information...

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Small Diamond Core Drills Versus Small Diamond Drill Bits

Small Diamond core drills will glide through the material a little easier and more quickly than the solid ended small diamond drill bits making them the ideal choice for beginners. 

However, the small diamond coring drills have a smaller surface area of diamond grit and have a core running through them which makes them slightly less robust and not quite as durable as the small diamond drill bits.

Users often keep a combination of both core drill and diamond tipped drill bit types in their tool kit, or you may find a personal preference for using one over the other.  

How to use Diamond Drill Bits:

You will need an adjustable chuck or collet to hold these small diamond core drills, take a look under the 'Technical' tab below to find out the shank sizes of these drill bits. 

If you have a Dremel rotary tool, we recommend the Dremel Multi Chuck. This allows you to change drill bit sizes quickly and easily.

Tip: The following three crucial elements when drilling will prevent the diamond grit from wearing off too quickly or burning away, will prevent the drill bit from snapping (from too much pressure applied), prevent your material from cracking, and extend the life of your drill bits.

  • Use with plenty of cold water (if drilling in a container, change the water when it turns cloudy)
  • Use on a slow speed, not exceeding 10,000 RPM
  • Use at low pressure, let the weight of the rotary tool do the work 

In order to get the best from our diamond tipped drill bits, please ensure you read through the Tutorials section on our blog before attempting to use our drills for the first time. Here you will find tips and video footage on how to drill glass, how to drill gemstones, how to drill bottles, how to drill pebbles and how to drill sea glass. There are also helpful hints on the correct speeds and pressure to be used.

You might also like to read our article: 12 Things You Should Know about Diamond Drill Bits

What is a Core Drill?

Our diamond core drills are designed to drill holes in very hard materials and they do this by removing a cylinder of the material. 

When drilling, the core drill bit enables water or lubricant to swirl up inside the core, preventing overheating. Overheating can cause your material to crack or break and will shorten the life of the drill bit.

Many of our customers use our core drill bits to achieve a core rather than to drill a hole. We can't guarantee the precision with which you might achieve the perfect core but many have done so with success.

From time to time the debris may become stuck in the core of the drill bit. If this happens it will often become dislodged when you begin drilling your next hole. 

Alternatively, use a wire brush to clean out the core of the diamond drill bit. 

To prevent your diamond core drills from clogging, drill in and out (up and down) as you drill to dislodge the debris. This will prevent the debris from being pushed up the core of the diamond drill bit.

If you are new to these diamond drill bits then our Infographic 'How to Drill Through Glass' has easy-to-follow steps. 

"I work in the Dept. of Facilities at the Natural History Museum and operate electron microscopes and electron microprobes. The material we analyse are usually rocks and we use the small core drills as well as 5mm, 26mm, 30mm and other sizes to cut cores" - John Spratt. Natural History Museum, London
"I use the diamond core drills on glass about 1mm-3mm thick and can normally drill between 200 and 300 hundred holes. The best ever result was 450 holes with one drill bit (impressive) I use slow speeds, always gently pumping up and down and drill constantly under water" - Ulrich Braunbeck"

Disclaimer. Using rotary tools near water has never been, to the best of our knowledge, endorsed by any of the rotary tool manufacturers. If you do choose to drill near water or with attachments under water connected to your drill then you do so at your own risk. Please be aware that mixing electricity and water can be very dangerous.


Diamond grit 120# is precisely electroplated onto a hardened steel shank

1.00mm Diameter core drill

  • Overall length: 60mm
  • Diamond working length: 3.0mm - 5.0mm
  • Shank: 0.75mm
  • Tolerance +/-0.1mm

1.50mm Diameter core drill

  • Overall length: 65mm
  • Diamond working length: 6.0mm - 8.0mm
  • Shank: 1.48mm

2.00mm Diameter core drill

  • Overall length: 65mm
  • Diamond working length: 4.0mm - 6.0mm
  • Shank: 1.50mm

2.50mm Diameter core drill

  • Overall length: 65mm
  • Diamond working length: 5.0-6.0mmmm
  • Shank: 2.0mm

3.00mm Diameter core drill

  • Overall length: 50mm
  • Diamond working length: 4.0mm
  • Shank: 2.70mm
  • Tolerance +0.1mm

Questions & Answers

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Other questions and our answers

Can these bits (small diamond core drills) be used with a Dremel rotary tool? Thank you in advance. Best regards, Silvio Berra

Silvio Berra

Hi Silvio, 

Thanks for your enquiry. Yes the small diamond core drills bits are ideal to use in a Dremel rotary tool, but you will need the Dremel Multi Chuck to hold the very small shanks of these drill bits. 

Hi, I want to order diamond bits to drill 1mm holes in 500um thick borosilicate glass wafer. Could you please tell me if 0.75mm diameter drill bit would be perfect for that or not. Also, what other items I would need to drill hole along with drilling machine. Besides, could you suggest me which drilling machine would be sufficient for this job. Thank you. Best Regards Deepika Sharma

Deepika Sharma

Hi Deepika,

Good to hear from you. We recommend using a Dremel 3000 drill with a Dremel Multi Chuck and use either the small diamond drill bits or the small diamond core drills. If you are new to drilling holes in glass we recommend trying the core drills first. The size of the core drill indicates the size of the hole you will achieve, so if you need a 1mm hole, you will need to purchase the 1mm diamond core drills. All the best with the project.

Will the small diamond drill bits work in a drill press ?


Hello Ann, Yes they work perfectly well in a drill press.  They will work in any drill so long as there is an adjustable chuck to hold the shank of the drill bits. 

Will your drill bits fit my drill?


Our drill bits will fit all rotary drills so long as you have an adjustable collet or chuck with which to hold the shank of our very small drill bits. Sometimes when buying a drill they will come with an adjustable collet but if you find you are in need of one then we supply either a Dremel Multi Chuck (DMC4486) or a Dremel Collet Nut Kit (DCNK4485).

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