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How Are Diamonds Cut?

by Lucy Coleman
Last updated on June 22, 2023
how are diamonds cut

When you think of a diamond, you’re probably thinking of a shiny stone in the classic shape of a diamond with a flat top, lots of sides, and a pointed bottom. This is the shape of the popular round brilliant diamonds, but no diamond starts out looking like that. Diamonds are minerals that form rough-looking stones. It takes precise cutting and polishing before it becomes ready for jewelry. If you’ve ever wondered “how are diamonds cut?” we’ll go over that, as well as why it’s important to know–especially if you’re shopping for a diamond.

What Is Diamond Cutting?

Rough diamonds look like small rocks without any sparkle or shine. A jeweler must cut a diamond into the proper shape and then polish it so it will look like the traditional diamonds you see in engagement rings and jewelry.

Diamond cutting is the process of shaving off part of the diamond until it is the right shape. The cutting process is arguably the most important factor in determining a diamond’s beauty, value, and quality. Skilled jewelers perform this delicate process with skill, expertise, and specialized tools.

Rough diamonds are first mined from the ground. Then, they go to main diamond trading centers where they will be processed before being available for retail.

The History of Diamond Cutting

Example of Indian Polki Cut Diamond Jewelry
Example of Indian Polki Cut Diamond Jewelry

Diamonds have been around for ages, with the earliest record of them (diamonds known as polki) in India for decorative and religious purposes. Diamond cutting as we know it today did not develop until the Middle Ages.

The diamond cutting techniques have evolved greatly since then from point cutting, the table cut, and the rose cut to the brilliant cuts we recognize today. Now, newer technologies are making the diamond cutting process even more precise and efficient.

The Steps of Diamond Cutting

Irene Ring. How are diamonds cut.

There are a lot of careful steps that go into cutting a single diamond. Here are some of the major steps so you can see what a diamond goes through before becoming beautiful jewelry.

Planning The Cut

Before a diamond cutter cuts a diamond, they analyze the rough stone for blemishes and internal flaws. Then, they plan out the cut to maximize the diamond’s beauty and value.

Since approximately 50-60% of the rough diamond gets cut away during this process, it is essential to map out exactly what the finished diamond will look like. The more a diamond is cut, the less carat weight it retains making it less valuable. By planning out the cut, the jeweler can maximize the carat weight, and oftentimes cut away parts of the stone that have flaws.

The next step is to mark the stone using a special tool called a diamond scribe. These guidelines help the cutter ensure the diamond is symmetrical; they also ensure the angles are precise.

Shaping the Diamond

1 1/2 CT. TW. CLASSIC 3 STONE PENDANT. How are diamonds cut.

The diamond cutter will use a saw to cut the diamond into the desired shape. The saw must be made of a hard material to prevent it from being damaged by the rough diamond. These saws require high speeds to ensure the cut is smooth and precise.

Diamonds must be cut with very special tools since they are the hardest mineral on Earth. Cutters may use a steel blade with a diamond coating to saw through a diamond.

Cutters may cleave a diamond rough on a weak point or split one diamond into two. This is why cutting requires careful planning beforehand so the cutter can maximize the perfect and strongest parts of a diamond.

After cutters saw the diamond, they shape it using a process called bruting. This shapes the diamond’s girdle, which is the upper part of the diamond. The bruting process also uses a wheel covered in diamond dust. It grinds down the diamond’s girdle, making it symmetrical and smooth.

Faceting the Diamond

Certified Emerald Diamond Stud Earrings

Faceting is the process of cutting and polishing the diamond’s facets. Diamond facets are the flat surfaces of the diamond that reflect light and are often called reflective facets.

A diamond’s cut grade is based on the quality of the facets which includes their size, shape, and symmetry. Diamond cutters use specialized knowledge and tools to create precise and even facets.

The round brilliant cut is the most popular diamond shape, and it has 58 total facets. Other diamond shapes will have a different number of facets. Generally, the more facets a diamond has, the smaller the reflections it will produce. Fewer facets aren’t a bad thing. It’s all about what complements the diamond shape the best.

Polishing the Diamond

Lab Grown Pear Shaped Diamond. How are diamonds cut.
Lab Grown Pear Shaped Diamond

While still important, a diamond’s polish grade is not as important as the cut grade. The overall cut of a diamond will affect the appearance of the diamond much more than polish lines or blemishes from polishing.

The final step in the cutting process is polishing. Polishing gives the diamond a smooth and shiny surface and really allows it to reflect light.

Special polishing wheels polish each facet of the stone. Cutters must be very careful in this phase because there are many blemishes that can occur from polishing.

Polish lines, nicks, and scratches can form on the diamond during polishing and decrease the value of the diamond.

Diamond polishing can still shave off some of the diamond itself so polishers must be careful if they want to maintain a certain carat weight. The actual carat weight of a diamond will be much less than the weight of the original rough diamond.

The GIA and Cut Grades of Diamonds

Round Bezel Engagement Ring
Round Bezel Engagement Ring

The Gemological Institute of America has created an internationally recognized system to grade individual diamonds on their cut quality.

Cut quality is the only major factor of a diamond that a jeweler or cutter determines, it’s not inherent in the stone itself. This means that diamond cutting is a skill that requires a lot of experience and practice.

The GIA breaks down cut quality into different cut grades and assigns a grade to each diamond. The grade depends on a range of factors including weight, symmetry, polish, and technical measurements. It isn’t based on appearance, but the cut quality will greatly impact the appearance.


Excellent diamonds have the best light performance, maximum light reflection, and perfect shape. They are the most brilliant and will sparkle more than any other diamond.

Very Good

Very Good diamonds have great light performance; they are cut in a way that maximizes light reflection. They have a lot of fire and are very brilliant.


“Good” diamonds have adequate light performance and reflection. They are considered to be beautiful and are featured in jewelry. They have a good amount of fire, brilliance, and scintillation.


Fair diamonds are acceptable, but they have poor light performance and brilliance. They do not reflect light as much which is very noticeable.


Diamonds with a poor grade have very poor light performance and are generally unattractive. They do not sparkle or shine like a diamond you would see in a store, and they may more closely resemble a rough stone.

What You Should Know About Cut Quality in Diamonds


While the cutting process may be lengthy and complex, you don’t need to remember all of the steps in diamond cutting. The most important thing to understand is the differences in the cut quality of diamonds and what to look for when shopping for a diamond.

Look for diamonds with Excellent or Very Good cut qualities for the brightest and shiniest cut diamonds. They will be so brilliant that everyone can’t help but notice your sparkling gem.

Cut quality is one of the factors you don’t want to sacrifice when buying a diamond. If you’re trying to save money, it may be better to save on color grade or clarity instead of cut because the cut quality will have the biggest impact on the appearance of the diamond. A poorly cut diamond won’t shine and will look dull.

You can also buy a lab grown diamond which can be 20-40% less expensive than a mined diamond. This way you don’t have to sacrifice sparkle and shine while staying within your budget for an engagement ring.

Diamond Cut vs Diamond Shape

People talk about diamonds in all sorts of ways, and it can be confusing to differentiate between diamond cut and diamond shape.

Diamond cut is the quality of the diamond’s cut and polish.

Diamond shape refers to the different possible shapes of diamonds like oval, emerald, pear, cushion, and more. There may be different types of diamond cuts depending on the shape.

You may often see diamonds labeled as emerald cut or princess cut. That refers to the shape of a diamond.

With any diamond shape, you want to make sure you choose a diamond with an excellent cut quality so it will sparkle as much as possible. Only round diamonds receive a grade based on the GIA grading scale.

The GIA does grade the symmetry, polish, and overall proportion of fancy shapes, so look for those when deciding if you want to buy a diamond.

Finding an Excellent Cut Diamond

Toi Et Moi Diamond Engagement Ring
Toi Et Moi Diamond Engagement Ring

Now that you know what to look for, you can find beautiful diamonds at Clean Origin for an engagement ring or other piece of jewelry.

When you’re looking for diamonds you want to look at the actual carat weight, color, and clarity, but make sure you pick a diamond with an excellent cut grade so you don’t end up with a poorly cut diamond. Round diamonds will sparkle and shine as much as you when you find the one that shows off your unique style.