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Small Diamond Core Drills


Bulk Discounts

Quantity Purchased Price
1 - 4 £5.95
5 - 9 £4.95
10 - 24 £3.85
25 + £3.45

Sizes Available: 1.00mm, 1.25mm, 1.50mm, 2.00mm, 2.50mm, 3.00mm

Similar to our small solid diamond drill bits but with a hole through the middle, these drill bits are hollow, allowing water to circulate inside the core. They are ideal for drilling holes in glass, sea glass,  tile, ceramic and porcelain, glazed pottery, beach pottery, beads, pebbles, stone, slate, petrified wood, fossilized bone, optical material, composites and rock. For those tough pieces of seaglass, they work like a dream! For very hard stone such as quartz try our small diamond drill bits

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You may 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 easily.

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. The core allows drilling with water or a lubricant to swirl up inside the core whilst drilling, 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 drill bit. To prevent this from happening, 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 drill bit.

If you're new to these drill bits then our Infographic 'How to Drill Through Glass' has easy to follow steps. If you would like to drill holes in pebbles, see our article:  'How To Drill Holes in Pebbles'

Tip: use with plenty of cold water, slow speed, low pressure

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 is precisely electroplated onto a steel shank

1.00mm Diameter

  • Overall length: 35mm
  • Diamond working length: 3.00mm
  • Shank: 0.75mm

1.25mm Diameter

  • Overall length: 35mm
  • Diamond working length: 3mm
  • Shank: 1.00mm

1.50mm Diameter

  • Overall length: 35mm
  • Diamond working length: 3.00mm
  • Shank: 1.15mm

2.00mm Diameter

  • Overall length: 35mm
  • Diamond working length: 4.00mm
  • Shank: 1.75mm

2.50mm Diameter

  • Overall length: 35mm
  • Diamond working length: 4.00mm
  • Shank: 2.15mm

3.00mm Diameter

  • Overall length: 50mm
  • Diamond working length: 3.50mm
  • Shank: 2.35mm

Customer Reviews

It's a drill, a small one.
stunning it did a perfect job
The product is great and goes through my seaglass like a knife through butter! However after about 4 or 5 pieces of glass being drilled, it gets quite blunt, and is time to change the drillbit, so it would be amazing if the product lasted a bit longer and were more durable. Although, i do understand that it is quite hard to achieve this as cutting through glass is bound to make the drillbit blunt! Would use again!!
job well done thanks will buy againg
great tools fantastic service and advice
Nice products. Exactly as described. 100%
Great product for what I need.
Product arrived quickly and purchasing was easy on their website
Best product out there for drilling stones and glass
Perfect for drilling glass from jewellery to hanging plaques.
As Above
Brilliant diamond core drill bits, will definitely buy from you again. The tiny one is very tiny, too small really for what I need but still works brilliantly.
Does exactly what they are meant to.
The quality of the drill bits I've purchased seems very good. The smaller diameter (1mm) drills bits seem to have a longevity/durability issue but that's probably my fault!
Excellent, I am very satisfied.
drilled hole in pebble. RESULT!
They make drilling glass a doddle :)
Works really well. The shaft is a bit soft and got crushed by the bit holder but didn't affect the use
As Above
Perfect for my glass-drilling needs
Does the job really well but has limited life...
3mm drill bits are great, not so sure about 2 mm they broke fairly quickly.
As Above

Questions & Answers

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Other questions and our answers

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).

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. 

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.

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. 

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