Skip to Content


Can Diamonds Cut Glass?

Can Diamonds Cut Glass?

As you probably already know, diamonds have multiple purposes. However, there is one topic around which opinions are divided, and it has to do with the ability of a diamond to cut glass. 

While some claim that this is possible, others dismiss it as pure fiction. There’s been a lot of discussions about this – and we are here to shed light on this discussion and settle it once and for all. 

So, can diamonds cut glass? 

The answer is yes, diamonds CAN cut glass – and many other materials as well. Okay, that was simple. Now that we’ve cleared that up, it’s time to focus on the details of glass cutting. 

To learn how to cut glass with a diamond, what other materials you can cut with them, and whether you should watch out for something, stay tuned until the end of this article!

Diamonds Can Cut Glass – No Question There!

When it comes to topics like glass cutting, it is always better to address them as soon as possible so that people do not get hurt while testing their own theories.

As far as the connection between diamonds and glass is concerned, diamonds can cut pieces of glass – and very easily, might we add. How is this possible? Easy. 

The explanation for this lies in the physical properties of diamonds. If you have forgotten about this, take a second and remind yourself of some of the following characteristics:

  • Hardness – A well-known and probably the most important characteristic of a diamond is its hardness. This refers to their resistance to exterior impact, and breaking the diamond into two or more pieces. In a few seconds, you will have a chance to see the precise measurement for this.
  • Color diversity – When you think of diamonds, you probably think of transparent ones. Today, however, diamonds are available in a variety of colors, and this is exactly what makes them stand out as jewelry pieces.
  • They can scratch anything – One way to check whether a diamond you own is real or fake is to try to scratch something. A real diamond will leave a mark on almost any surface. We’ll talk about this more shortly.
  • Not see-through – The difference between a real diamond and a regular piece of glass is that you shouldn’t be able to see anything through a real diamond.

Mohs Scale Of Relative Hardness

The Mohs scale has been a reliable indicator of the hardness of minerals since 1812. This scale is straightforward to follow and measures a mineral’s hardness from 1 to 10.

It’s pretty simple, really. The higher the rating on the Mohs scale, the harder the mineral. A diamond carries the highest possible rating – which is a perfect 10 – and because of that, diamonds can cut almost any surface.

For a better understanding, let’s look at the hardness of a diamond in relation to some other minerals that are known to us.

9Sapphire, Ruby
5Apatite, Glass
3Copper Coin

What can we conclude from this table? After you take a closer look at the hardness of the minerals mentioned above, you can conclude two things about diamonds and glass:

  1. Only a diamond can scratch another diamond. 
  2. Glass can only scratch minerals with a rating lower than 5.

Granted, ordinary glass plates will have a hardness of 5. But generally speaking, it can vary from 4 to 7 depending on the type.

Testing Hardness

Whether you are testing a diamond, glass – or any other material – for hardness, there’s a specific procedure that you must follow. Don’t worry; it’s nothing too complicated. 

It’s actually pretty easy to check the hardness of an unknown material. All you have to do is follow these steps:

  1. Take the item of unknown hardness.
  2. Look for a smooth surface for testing purposes. Make sure it hasn’t been scratched before. 
  3. Hold the surface on which you are doing the testing and the item you are testing firmly so as not to scratch something you do not want.
  4. Press the item of unknown hardness to the surface and slowly draw a line.
  5. After you’ve done this, wipe off the residue if there is any left, and take a good look at the surface you have just scratched. You can also use a magnifying glass.

Possible conclusions are as follows:

  • If the item of unknown hardness (A) scratched the surface on which you performed this (B), then A is harder than B.
  • If the item of unknown hardness (A) did not leave any marks on the surface on which you performed this (B), then B is harder than A.
  • If both items (A and B) showed signs of scratching, then their hardness is equal.

Caution: Working with certain minerals, such as diamonds, can be dangerous because of their sharpness. We recommend that you use protective gloves if you have them.

Glass Vs. Diamond – Who Would Win?

Since we are talking about the ability of diamonds to cut glass, perhaps some significant differences between these two items can help. We can often tell them apart with the naked eye – but how much do we know about them?

So far, we’ve managed to establish the difference between the hardness of these two items, but how sure are we regarding some other features? 

Let’s recap.


There’s a huge difference in terms of the composition of diamonds and glass.

As far as we know, commercial glass consists of three main “ingredients,” which are sand, limestone, and sodium carbonate. This glass is the most produced one in the industry and comes in all shapes and sizes.

On the other hand, natural diamonds consist of carbon and NOT coal, which is a very common misconception. The arrangement of carbon atoms within a diamond gives it the signature physical and chemical properties.

You should check out: What Is The Difference Between Diamonds And Coal?


When it comes to the difference between the look of a diamond and glass, this is very easily noticeable by the naked eye. All one needs to do is take a closer look at these two items.

Diamonds are not as transparent as glass! 

Glass is made so you can clearly see through it – but you shouldn’t be able to see through a diamond.

Appearance also includes colors, and there is not so much difference here since both diamonds and glass can come in a range of colors. But no color is what comes to mind first, right?

In addition to being different in appearance and composition, even the most valuable diamonds have flaws and scratches on their surface. That’s nothing to be worried about, though. It’s actually what makes them real -because perfect usually means fake.

Glass, on the other hand, cannot afford to have any scratches. 

If you think about it for a second, would you like to see dozens of tiny scratches on your window?

Discovered Glass Harder Than Diamonds?

Scientists in China have recently been preoccupied with discovering and testing glass that is harder than diamonds. Reportedly, this glass is made mainly from carbon.

The current name of this discovery is AM-III glass, but we are sure that this will change over time. Currently, this glass is in the testing phase and far from any mass production.

The primary idea behind this carbon-based glass is to make it bulletproof.

Learn More: Are Diamonds Bulletproof? Can A Bullet Break A Diamond?

How To Use A Diamond Glass Cutter? Quick Guide

If you think you have the skills, then the following glass cutting guide will be helpful. If you stick to the steps outlined below, we’re sure you won’t have any problems – provided that you have the necessary knowledge and equipment.

Let’s get to work!


  • The first thing you need to do is look for a surface on which you will cut the glass.
  • Look for a surface that is soft, and make sure to add a working carpet so as not to scratch the rest of the area.
  • Take a damp cloth, and thoroughly clean the surface of the glass you are going to cut. Make sure you don’t leave any stains.
  • Take a glass cutter. That is a crucial part of this guide. Most glass cutters you use have a built-in diamond at the top to mark the lines you will cut.
  • Take some cutting oil. You’ll need this to provide proper lubrication. 
  • Carefully measure and mark the lines where you will make the cut. Since glass is fragile, we recommend using a ruler for more precise measurements. Be careful because once you mark this with a diamond cutter, the lines cannot be erased.


  • Take your glass cutter and dip it slightly into the cutting oil. Make sure nothing drips from your glass cutter onto the surface you are cutting.
  • Position your ruler at the angle you are cutting, and slowly press it with your hand so that it does not move.
  • With your other hand, hold your glass cutter and draw the first line. As you draw the line, make sure that it doesn’t make a loud sound.
  • When you have finally made the line, slowly remove the ruler and your glass cutter to the side. Be careful not to leave traces of oil.

Tip: If you press the glass too hard with your glass cutter or hand, it may break.


  • Once you have successfully drawn and carved the lines into the glass, it is time to break it into the desired shape. You mustn’t rush this part!
  • If the glass is smaller, take it in both hands, then slowly try to apply pressure, and finally cut it in half.
  • If it is a larger piece of glass, slightly press the glass with one hand and try to break the other part with your other hand.
  • After breaking the glass, take a good look to see if any small particles have fallen to the floor or if there are any on the surface you are cutting. Clean up everything!

What If You Want To Cut A Curve?

The guide you just read was about cutting at 90-degree angles. However, what if this is not your initial wish, and you want to cut a curvy piece of glass?

The procedure is almost identical. 

Preparation and scoring of the glass will follow the same principle. The only thing is that now you will not need a ruler – but you will draw lines with your hand freely.

When you get to the breaking part, you’ll have to be a little more careful.

Curved glass is broken by turning it to the other side and lightly pressing the points where the curves are located with your hand. When you feel the glass has loosened up, try to break it in half.

If you think you are not experienced enough with a glass cutter, and you happen to have cut the glass unevenly, try using a spinning wheel with built-in diamond chips to smooth out the surface.

Related Read: An In-Depth Guide on Diamond Cutting: How Are Diamonds Cut?

Wrapping Up

Today, we dealt with a topic that is very well known but insufficiently researched – can diamonds cut glass? Despite all the misconceptions, we managed to make a clear point and explain it:

Diamonds can scratch and cut glass. In fact, diamonds have the most extraordinary hardness according to the Mohs scale, and they can scratch anything weaker than them – which turns out to be, well, everything.

When it comes to glass and diamonds in particular, we can easily distinguish the two. Diamonds are harder; they are not see-through – and one can notice numerous flaws on the surface.

If you want to cut glass, you can do so by using a diamond-based glass cutter for easier scoring. You can make straight or curved lines – but make sure you do it safely!

Learn More: Why Is Diamond So Hard?