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Why Is Round Brilliant Cut The Most Popular Shape of Diamond?

Why Is Round Brilliant Cut The Most Popular Shape of Diamond?

“Diamonds are a girl’s best friend,” said Marilyn Monroe back in 1949 – and that hasn’t changed so far! 

But some things have happened when it comes to the gemological industry since modern-day technology was introduced – and a few new interesting shapes of diamonds are now the center of attention.

Still, one shines brighter than others, in more ways than you might think – and that’s why you’ve probably heard of round brilliant cut diamonds. But what makes them stand out and take up to two-thirds of the total diamond cut sales?

If you’re interested in learning why this cut remains the indisputable winner amongst all others, we’ve prepared some dazzling answers right here!

What Is A Diamond Cut?

Before we get into spelling out the name of the diamond cut you’re here for, you should know a few things about the term “cut” itself. The term can easily be mistaken for shape – and even though they’re essentially the same, the meaning is different. 

The “shape” refers solely to the form of the diamond figure – such as marquise, baguette, pear, emerald, and, of course, round. There are many more that fall into the same category of basic shapes. Maybe the early artisans had even more ideas – but no technology to go along with them.

Since that’s no issue in modern-day times, an interesting new category of diamond shapes has shined through – resulting in exotic and thus rare diamond cuts. They include kite, briolette, drop, lozenge – and many more.

“Time’s of the essence” can be a term related to diamonds, too!

That means there’s a category of old diamond cuts that could be considered antiques. They’re rarely seen in jewelry stores since they require special skills and heritage practices to be made. They include old single, old European, Peruzzi, rose, and a few more.

In that matter, the jewelry embellished by these stones is considered antique – when older than 100 years – and vintage, when somewhat “younger.” 

On the other side of the coin, very recently, new interesting cuts were carved by exceptional masters of the trade – such as my girl diamond, the eight hearts diamond, and the criss cut. And all of these shapes are referred to as fancy ones, but only the round is a classic exception in the industry!

As you’ve just seen, there’s an overlap between the two terms – shape and cut – but cut carries a bit more meaning: It’s a description of how well the diamond’s facets interact with the light, the proportions of the gem, and the overall finish of the stone. It’s easily confused with facet arrangement, such as brilliant or trilliant. 

All things considered, a round brilliant cut diamond has a round shape with a distinct position of facets – that you’re yet to be dazzled with – and is cut with a particular skill.

So, there you have it: The gem’s cut describes the overall craftsmanship of the stone and how it affects the diamond’s brilliance!

Diamond Brilliance: Why Is It Important?

Brilliance represents the most important play of light in a diamond. Before we sway with the meaning, you should know something about the reflective surfaces that are needed for the phenomenon.

The diamond surface is made of so-called facets, and a facet (in singular) refers to one side of many. They’re often organized in a way to form specific segments:

  • Table – The large top that helps gather light
  • Crown – The upper part that’s most responsible for the shine
  • Girdle – The perimeter facets
  • Pavilion – The bottom half
  • Culet – A tiny flat facet on the bottom

And the skill by which these stone parts are detailed defines the cut. They come to be modeled by a lapidary – and we’ll get to that in just a bit. 

A smaller fraction of light reflects off of the facet – it retracts, but most of the light beam makes it through the facet wall and into the stone center. At that point, the ray reflects among the internal walls of the facets just like it would if mirrors stood in their places. 

And just like we have different dancing styles, so does the light! Brilliance is achieved by controlling the direction the light waves go after they enter the diamond in the described way. The goal is to “bend” the light rays coming from any angle, so they exit the diamond at the top – at the viewer’s line of sight. And if achieved, this kind of reflection is called brilliance!

A diamond with facets positioned in a certain way is accordingly called a brilliant – but more on that in a moment. To learn more interesting information on brilliance, take a look at this article.

Diamond Shine: Is There More Than Brilliance?

The answer is “Yes,” and even though brilliance is the one you most likely heard of, gemologists hold two other reflections accountable for the diamond sparkle.


Sparkle is the life of a diamond – but it is rarely mentioned since it can seem similar to brilliance!

Scientists believe it’s extremely neglected, and 15 years ago, a pioneering, one-of-a-kind study was made courtesy of AGS, in which scintillation is described as the most appealing of all light plays that are seen in a gem.

The fire pattern changes dramatically, and flashes of white light can be seen across the crown of the stone. So, we can say there are two separate scintillation aspects in a diamond sparkle – fire and flash. Both happen solely if there is movement – of the stone, the light source, or the viewer!

And the trick is directing the light waves across the diamond body, opposed to just the top of it, but in the viewer’s eyesight, as well. Then it seems as if they’re skipping between the facets. 

The sparkle is desirable in all of the crown facets, and a poorly cut gemstone has “dead” areas where there are no flashes at all. Flash scintillation is more common since it happens in a broader range of light environments – and, in this case, white flashes can be seen. 

That’s why you’ll most likely see diamonds exhibiting white shine.

On fewer occasions – in fire scintillation – the colored light rays of the fire phenomenon will be seen “skipping” in such a manner. To find out something more about scintillation in diamonds, take a look at this article

But what’s the mentioned fire in a diamond? 


Fire refers to the colored flashes you see seemingly trapped inside your stone. The light ray entering the diamond is by nature white light, and after it “bounces” a few times off different facet walls, it’ll disperse into a rainbow of colors that are part of white light.

Red, orange, yellow, blue, green, and violet all bend and reflect differently. The further the light ray goes while bouncing, the more dispersion will occur – while the remainder of the white light will exit the gem through the facets.

Diamonds are known as irrefutable when it comes to dispersion amongst all existing materials! There’s one more light phenomenon, but since it’s the only one that has little to do with cut, we’ll leave you to read more about diamond fluorescence here.

What Has Cut To Do With The Diamond Shine?

Sculpting a diamond outline tests the artisans in arranging the position of the facets. And that makes the cut most crucial out of the 4C’s since it determines all else – clarity, color, and carat

Every bought diamond comes with a report of information about it, and round brilliants have a GIA Diamond Cut Grading System all to themselves. It’s a D-Z color range in which seven components are appraised. 

The first three are the described plays of light, and they’re appearance-based. The remaining four – symmetry, durability, polish, and weight ratio – belong to the craftsmanship and design of the stone. 

In every assessment, the relative value of each of these properties is taken into consideration. Accordingly, there are many different combinations that depend solely on the buyer’s “taste” and preference.

The cut grade is based on a scale of 0-10, ranging from Poor to Excellent – in which a diamond has an even pattern of bright and dark areas. That, for example, is the doing of scintillation.

AGS composed a slightly detailed scale, with “Ideal” as the highest value. It’s known as the pinnacle of the cutting industry, so there’s a difference when the jeweler tells you a gem is ideal – and when it’s, in fact, AGS Ideal. 

So, if the cut is made right, posing a smaller stone against a bigger one with a lesser cut value will make it seem more prominent!

The Diamond Cut: How It’s Achieved

Diamond cutting was supposedly first tried circa 300 BC in India and has come a long way since then. It was sort of expected for Indians to excel at mastering the craft since diamonds were first discovered there, too. 

Many famous diamonds, like the Koh-I-Nor, were their artistry. However, the European masters weren’t so far behind. Some travel notes of Tavernier from the 17th century even mention Europeans as the diamond cutters working in India – although it’s unknown if they were apprentices or the actual masters of the craft. 

In any case, the cutting process was the polishing phase of today, and if some impunity was too deep, they used to glue additional facets in that place. In time and after the discovery of the cutting wheel, cutting became a sophisticated process that now comes in four phases: 

  1. Cleaving – Cleaving alongside the diamond’s tetrahedral plane to give it a manageable size and later cutting it in two.
  2. Sawing – Roughly determining the table and the girdle while cutting in places where it’s not weak.
  3. Cutting/Bruitting – Determines the outline of the diamond exclusively with another diamond, and it can be done by hand (bruiting) or by a machine (cutting). 
  4. Polishing – The finest details are usually accomplished with diamond powder to create a smooth finish for the light rays to enter. 

But there’s something specific in round brilliant diamond cutting. 

It was discovered by Belgian engineer Marcel Tolkowski, with his findings published in his book titled Diamond Design in 1919. This gemological holy grail states that the stone is to have a 53% table, 59% total depth, and a knife-edged girdle. 

Slight moderations to his proportions were made, and those included a closed-up culet, a larger table, and an extended lower half. And little by little – by the time of 1950 – the round brilliant cut was created as the summary of perfectly determined characteristics. 

A brilliant is a round stone made out of 57 facets – the 58th one being the optional culet.

They’re always arranged so that the table is the most prominent part, but the lead role is played by the crown that consists of eight bezels, eight stars, and 16 upper halves. They’re responsible for the previously described light plays and the bright-dark pattern. 

The pavilion facets consist of 16 lower halves, eight mains, and maybe a culet, all reflecting the light waves in described ways – back through the crown.

But that wouldn’t be possible without modern-day technology. One of those inventions was the Firescope that made visible to the viewer that a diamond cut in the described proportions has a “hearts and arrows” pattern. 

Then came inclusion-mapping software and high-speed laser cutting. But most important is the scientific approach needed to understand the round brilliant cut – that means examining all the appearance aspects separately.

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

Final Decision

The cut is the most crucial property of them all, and it’s not to be mistaken for the shape of the gem. Instead, it’s a statement of the quality in which form takes part. 

Over time, many interesting diamond cuts were modeled, and despite that fact, there’s one still dominating the market and defining perfection. Diamonds cut in this way have a round shape made of 57 to 58 specifically arranged facets, in which the pattern of scintillation is equally balanced between the dark and the bright ones. 

These are round brilliant cut diamonds. And since they have proportions that can offer maximum light reflection – they can cost as much as $50,000 a piece!

Learn More: Price List: How Much Is A 0.1 To 40 Carat Diamond Worth?