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

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

Diamonds are not only beautiful but also one of the hardest substances found on Earth. But, if diamonds are the hardest substance, how are they cut?

Diamonds come in various cuts and shapes that emphasize their beauty and shine. You may think that a diamond’s shape is the same as its cut, but this isn’t true.

While the shape contributes to the overall style of diamond jewelry, the cut has a different role.

The cut is one of the 4Cs in diamonds. It’s more about geometry, science, maths, and light reflection than style and elegance. A diamond’s brilliance, fire, and scintillation depend on its cut.

Together, the cut and shape give a diamond its beauty and sparkle.

Cutting and shaping a diamond is by no means an easy task. Diamonds rank 10 on the Mohs scale of hardness, meaning they’re among the hardest substances on Earth.

That said, it’s only natural to ask yourself: If diamonds are the hardest substance, how are they cut?

Learn all about diamond cutting and how it’s done in this article.

Why Are Diamonds Hard to Cut?

Diamonds are hard to cut because of their unique molecular structure and composition. They’re a special form of carbon that can emerge only under specific conditions under the Earth’s crust.

It takes immense temperatures and pressures for carbon to be compressed into the state we know as diamond.

In nature, it takes billions of years for a diamond to form. However, the conditions under the Earth’s crust can be reproduced in labs with special equipment and technology.

These diamonds are called lab-grown diamonds. Their only difference from natural diamonds is their origin.

To explain why diamonds are so hard, we’ll need the help of chemistry.

The outer shell of each carbon atom in a diamond has four electrons. These electrons are shared with the other four carbon atoms. This type of bond is called a covalent bond and helps create the diamond’s crystal lattice.

The specific arrangement of atoms in a diamond’s crystal lattice makes them so hard to cut. When looking through the geological aspect, diamonds rank 10 on the Mohs scale of mineral hardness.

The Mohs scale measures how much a mineral can resist scratching, where 1 means almost no resistance and 10 ranks extremely resistant.

Without getting any deeper into the scientific details of diamonds, we can conclude that diamonds are the most resistant mineral on Earth, thanks to the rigid three-dimensional arrangement of atoms in their crystal lattice.

Knowing the science behind the hardness of diamonds, let’s find out who can cut them.

Who Cuts Diamonds?

The person specializing in diamond cutting is referred to as a gem cutter or lapidarist.

The term gem cutter is relatively new, while lapidarist has been used since the 14th century. In Latin, lapis means stone and hence, the name for the profession.

Before modern technology, lapidary was considered to be a form of art like sculpting. Similar to a sculptor, a lapidarist shapes precious stones and minerals into decorative pieces.

Being a professional gem cutter requires special education, expertise, a lot of practice, the necessary equipment, and patience.

Related Read:

Do Jewelers Cut Diamonds?

While some jewelers are specialized in cutting diamonds, most of them can only make small changes. Jewelers usually do things such as diamond resetting and repairs that don’t require hard work.

Diamond cutting, on the other hand, is a different story. It requires much more expertise, equipment, and labor to cut a diamond professionally.

Related Read: Can Jewelers Cut Diamonds?

What Makes Diamond Cutting Possible?

You may ask yourself, If diamonds are the hardest substance, how are they cut? Is there another substance able to cut diamonds?

Well, the answer is that only a diamond can cut another diamond!

Diamond dust is applied to bronze or steel saws. The diamond particles serve as an abrasive that helps cut and polish diamonds.

However, the actual thing that makes diamond cutting possible is the diamond’s anisotropy. When a material is anisotropic, it means that its properties are not equal in all directions.

A perfect example of anisotropy is wood.

As a kid, you probably had to shave your pencil from time to time in school. If you’ve ever played with pencil shavings, you’ll know that you can rip them easily parallel to the direction of the fibers. On the other hand, ripping the shaving is much harder perpendicular to the fibers.

This phenomenon is what’s called anisotropy.

In diamonds, crystals can be oriented differently, making it possible to cut a diamond along them. This is sometimes referred to as the diamond’s weak side.

While cutting diamonds is possible because of anisotropy, it’s not nearly as pronounced as in other materials such as wood and graphite.

Tools Used for Diamond Cutting

There are many tools a gem cutter uses to shape and cut a diamond.

When a diamond comes out of the mine, it doesn’t look like the diamonds you see in shops. Some would not even recognize it because it looks cloudy, rough, and has jagged edges.

Before a diamond cutter does its magic, there’s no brilliance and transparency we’re used to when seeing diamonds.

To achieve the sparkling elegance diamonds are famous for, a gem cutter needs to have professional equipment, including:

  • Workbench – The workbench is where the gem cutter does all their work. The more equipment they have, the bigger the workbench needs to be. Moreover, gem cutters who have been in business for a long time usually have more than one workbench.
  • Colander – A gem cutter will use a colander to wash the gemstones they cut.
  • Loupe – The loupe, or magnifying glass, is used to detect any damages and imperfections on the diamond.
  • Trim and slab saw – Trims and slab saws are special equipment that has blades made from diamond-tipped phosphor bronze or diamond-dusted steel. Slab saws are used to cut larger diamonds, while trims are intended for cutting small stones.
  • Rock tumblers – These are machines used for polishing and rounding diamonds.
  • Faceting machine – As its name suggests, a faceting machine is used to create the facets in a diamond. It features a mechanical arm, lap, and a water cooling system with which the diamond’s surface is flattened.
  • Rotary tools – These are all the tools a gem cutter may need for shaping, grinding, and polishing a diamond. Moreover, these tools may also include different attachments for machines used for cutting.
  • Cabochon templates – When the diamond needs to be cut in a special way, the gem cutter will use cabochon templates.

The Process of Diamond Cutting

Diamond cutting isn’t just grabbing the trim or saw and just slicing the diamond. It requires quite some work before a diamond reaches its peak of beauty.

So, let’s take a look at the diamond cutting process:


Planning is essentially designing the diamond’s future shape and cut.

In the past, lapidaries made sketches of the diamond on paper before moving on to the actual cutting. Today, designing the future shape of a gem is much easier, thanks to CAD programs.

Not only is sketching and visualization easier, but the whole planning process has become time-efficient.

Sawing and Cleaving

When the planning is done, the lapidarist can move on to shaping the diamond. Shaping is done by cleaving or sawing.

Diamonds that have a weak side are easier to break into parts. After the diamond is broken down into more diamonds of manageable sizes, the gem cutter will work on each of them separately. This process is called cleaving.

Sawing is used when cleaving isn’t an option. Essentially, sawing a diamond means shaping it without breaking it apart.

When sawing, the gem cutter will need to decide on which part of the diamond should become the girdle and which part will be the table.


Girdling, also known as bruting, is done by a machine that grinds the diamond and creates a rough finish. The actual tool that sands the diamond is similar to something you would encounter when visiting your dentist.


After the diamond got its rough finish, it’s time to make it smooth. Polishing involves the use of several brushes to remove even the smallest imperfections.


Once everything is done, the gem cutter needs to do a final inspection of the diamond. If the diamond meets the manufacturer’s specifications, it’s ready to leave the workshop.

What Happens After a Diamond Is Cut?

When a diamond gets its final cut and shape, it’s sent out to be graded. A certified gemologist will create a grading report on the diamond based on the 4Cs – cut, clarity, carat, and color.

Once that’s done, the diamond is ready to become someone’s pendant, engagement ring, earring, or other jewelry.

Learn More: Diamond Shapes: All Different Types of Diamond Shapes

How Were Diamonds Cut in the Past?

Diamonds can be cut both by hand or by using machines. However, before modern technology, they were only cut by hand, which was not nearly as perfect as today.

The first cutting and polishing methods began in India, where the first discovered diamonds came from. At first, diamonds were used as loose and uncut stones. No cutting or shaping was done until the 14th century.

Initially, diamonds were only polished by using a chisel. It was not long after that the first point cut was made.

Point cutting was the first faceting technique in history and was the only one for a long time. The next cutting techniques were the table and step cut.

Diamonds were cut by hand using only simple tools until the late 1800s, when cutting machines were invented.

The early steam-driven bruting machines and motorized saws enabled lapidaries to make various cuts for rounder and shinier diamonds.

Related Read: When Did They Stop Cutting Diamonds by Hand?

How Long Does It Take To Cut a Diamond?

Roughly, diamond cutting takes around 4-8 hours. However, this is only the time a machine needs to cut a one-carat diamond in the shape you want it.

When you take into consideration planning, polishing, grading, and transporting, it will take much more for a loose diamond to be ready for the store.

How Much Does Diamond Cutting Cost?

When it comes to the cost of diamond cutting, it can get quite expensive. The cost mostly depends on the size of the diamond because cutting is charged by carat.

Roughly, diamond cutting costs around $150-$400 per carat on average.

Take note that this is only a really rough estimate. Carat weight isn’t the only thing that can drastically change the price of diamond cutting.

The shape will also play a huge role in the final price of cutting. Moreover, the cost will rise even more if you need one diamond broken down into smaller ones that all need to be cut.

Learn More: How Much Does It Cost To Cut A Rough Diamond?

Is Diamond the Hardest Substance on Earth?

Interestingly, diamonds aren’t the hardest substance on Earth. However, they’re the hardest naturally occurring substance. Two substances on Earth are harder than diamonds:

  1. The first one is wurtzite boron nitride, which is a lab-made nanomaterial. It’s used for manufacturing traditional cutting and grinding tools.
  2. The second one is lonsdaleite. This is a substance similar to diamonds found on meteorites. It’s often referred to as the hexagonal diamond because of the shape of its crystal lattice.


Diamonds really are the hardest substances found on Earth. That’s why only a diamond can be used to cut another diamond. However, even this wouldn’t be possible if diamonds weren’t anisotropic.

Professionals who cut diamonds are called lapidaries or gem cutters. They cut diamonds by hand or with the help of machines.

Modern technology and tools have made it possible to create various cuts and shapes in diamonds. Moreover, gem cutting is now more time efficient than ever.

Diamond cutting can be quite costly because it requires experience and adequate equipment to bring a diamond in peak condition.

We hope this article has answered all your questions about diamond cutting and that you found the hard facts interesting.