Round Cut Diamond Shape Explained (Plus Buying Guide)

Last Updated on January 19, 2023 by Juli "Jewels" Church

Looking for an expert guide on round cut diamonds?

Perfect, you're in the right place!

In this guide, you'll learn:

  • What is a round cut diamond?
  • Pros and cons of this diamond cut?
  • How to save money when buying a round cut diamond?
  • Where is the best online store to buy a round cut diamond?
  • And much more!
round cut diamond buying guide

When you choose a round cut diamond for you or your fiance's diamond engagement ring, you are choosing the fairytale diamond shape.

When most people picture an engagement ring, they picture a round cut diamond. They are the top of the sparkle spectrum and will draw the attention of everyone in the room.

You'll love how a round diamond goes in almost any setting or ring style. 

Diamond cutters have got the beauty of a round cut diamond down to an exact science and mathematically equation for the highest quality diamond shape in the jewelry industry.

The light that passes through the diamond allows for a sparkle unparalleled to any other diamond shape. The round cut diamond is truly timeless, being at the top of both modern and vintage ring settings. 

But is a round cut diamond right for you? Don't worry, we'll help you figure out if the round cut is the best choice for you and your needs. Let's check it out!

Read Also: Where is the best place to buy an engagement ring?

What Is A Round Cut Diamond?

Round cut diamonds are diamond cut to perfect symmetry and proportions in order to display the most return of light, or brilliance, in a diamond. Also called round brilliants, they are the most popular diamond shape and the most expensive. They are the first diamond shape invented. 

Around the 15th century, it was discovered that you could facet rough diamonds into gem quality by using diamond dust. Once they got that figured out, they began experimenting with diamond cutting.

Of course, the diamonds back then were nothing like the dazzling diamonds we see in jewelry stores today. Today round diamonds are faceted by a technique called a brilliant cut, giving them their round brilliant name. 

Read Also: Round cut vs princess cut, which is better?

The early "round cut" diamond was originally named, the Old European cut. This was the round cut before the idea of brilliant cut technology came out. The Old European cut had deeper proportions and smaller tables.

And they weren't near as pretty are they are today. Back then, there were no such thing as diamond grades. In fact, the weren't sparkly either.

Diamond cutters didn't know how to optimize the return of light, so diamonds appeared grayish. That's also why colored gemstones were used in jewelry for royals and wealthy families. 

After the invention of the brilliant cut, diamonds became a thing of beauty and an object of desire. And as time went on, more and more was discovered about the most beautiful diamond shape on earth, at least, according to the professionals. 

Pros And Cons of Round Cut Diamonds

As with any diamond shape, the round cut has both highlights and drawbacks.

But are these drawback deal breakers? You be the judge.

round cut 14k white gold diamond engagement ring


  • Best brilliance of all diamond shapes
  • Easy to find
  • Exact cut grades and reporting
  • Doesn't need high clarity grades to look good
  • Fits a multitude of ring settings


  • Needs larger carat weight to be "seen"
  • Most expensive due to popularity and how much rough is discarded while cutting
  • Very common/not unique

How To Choose A Round Cut Diamond?

Once the brilliant cut was invented by Marcel Tolkowsky in the 1900s, the world of diamond quality was evolving. Diamond cutters now had knowledge of exact symmetry and scintillation to create ideal cut diamonds.

While the GIA doesn't officially recognize the ideal cut title, they do set forth the standard in which all diamonds are graded: the 4Cs. The 4Cs are diamond cut, clarity, color, and carat weight.


The round brilliant diamond is the only diamond shape that has ideal proportions with exact symmetry. There are some princess cut diamonds that are titled as ideal cut, but there is no set standard on princess cut diamond.

But a round brilliant, they had the highest percentage of light reflection due to Marcel Tolkowsky's mathematician side. 

When shopping for a round cut diamond whether online or instore, you need to make sure it has a grading report from either the GIA or AGS.

Grading reports from these labs are the most respected in the industry and lets you know that you can be sure the diamond grades on your report are accurate as sold. Other grading labs such as the IGI or GSI have looser guidelines in determining diamond grades. 

A GSI report may display a one carat round cut engagement ring as an SI1, H in color grade, and Excellent cut. But, it's possible to send that same one carat round diamond to the GIA, don't be surprised if it comes back as an I1, I in color, and a Very Good cut.

Not fair, is it? You can pay more for lesser quality with other labs, so it's best to stick to GIA and AGS grading reports. 

The cut grade system for round brilliant diamonds set by the GIA include 5 grades: Poor, Fair, Good, Very Good, and Excellent. You also might've heard of ideal cut diamonds, but the GIA doesn't recognize them. Excellent graded diamonds are GIA's equivalent to the American Gem Society's ideal cut grade. Excellent cut grades= ideal cut. 

Ideal cut diamonds are exact symmetry and carry the best sparkle of any diamond shape. But as you dive in the realm of ideal cut diamonds, you'll come across a few terms in your research you might need to know. Hearts and arrows pattern diamonds are prevalent in the diamond industry, especially online. 

In these diamonds, they are precision cut to create right angles that display hearts and arrows when looked at through a special tool. But some of the hearts and arrows patterns round diamonds you might see at fine jewelry retailers may display it through their gemscope. 

But just because a diamond displays the hearts and arrows effect, doesn't mean it is properly proportioned. You should always look at proportions of the diamond before falling for fancy words.

Super ideal cut diamonds are another gimmick, but really display no noticeable difference from an ideal cut, except a jump up in price. 

In order to understand the ideal proportions, you'll need to understand diamond anatomy. Thankfully, you don't have to be a gemologist to understand this. These are the different parts of the diamond: 

diamond parts

The whole viewable top of the diamond is referred to as the crown and the entire bottom is called the pavilion. If these proportions are not cut to the best quality, they are susceptible to breakage.

Lower cut grades like Poor and Fair can compromise the integrity and beauty of your diamond as well as its durability in a ring setting. Cut grades are the most important C of the 4Cs. It is the foundation of your diamond.

For this reason, your grading report should be at least a Very Good cut grade. You don't need anything more than an Excellent or Ideal cut grade. 


Because round diamonds are a brilliant cut, it allows you to choose a lower clarity grade than other fancy shapes. The sparkle in brilliant cut diamonds display a fire that hides inclusions that might otherwise be visible in an emerald cut diamond, which is a step cut diamond. 

The diamond clarity scale set by the GIA includes clarity grades of the following: VVS2, VVS1, VS2, VS1. If you have seen the phrase VVS diamonds and wondered were it came from, now you know!

In fact, with all diamond shapes, you don't need flawless diamonds. Step cut diamonds do need higher clarity because of their broad flashes, but you still don't need high clarity grades like VVS1 or VVS2. Diamond clarity for round cut diamonds is SI1. Minimum clarity grade should be SI2. 

While a clarity grade is only number and letters, it's important to view the stone as a loose diamond. All diamonds carry natural inclusions or blemishes, but no two diamonds are the same.

Check out these two SI1 clarity grade diamonds. With all other diamond grades the same and price very close, which one would you want? The SI1 with the blemish near the girdle, or the black inclusion right there in the middle of the table?

This reason is why you can't go on diamond clarity grades alone. You need to see the diamond under magnification. James Allen's 360 viewing technology is our favorite way of sorting out diamond clarity in round diamonds. 


Color grade is also not as important in a round brilliant cut than other fancy diamond shapes. The minimum diamond color grade needed for a round diamond should be I.

A diamond's color grade is graded on a scale of D-Z, however nothing further than K is used in retail. The range to stay in for all diamond shapes is the colorless to near colorless. 

But, you really don't need a colorless diamond, or a diamond with a color grade of D-E-F. With a round brilliant diamond, we recommend a minimum of I color grade, though you can find Js that don't look yellow.

If you choose to set your diamond in a yellow gold diamond engagement ring setting, your J or even a K will appear whiter than it is. This can save you even more!

You really shouldn't need anything an H color grade in a round brilliant diamond. It's a general known fact in the jewelry world that you really can't notice the difference between two adjacent color grades.


For most diamond shapes, we don't put a lot of weight (pardon the pun), in carat weight. We usually leave it up to buyer and regard it as the least important C.

Round diamonds that are 1 carat appear smaller than most other diamond shapes. If the size of your center diamond is important to you or your ring setting, you may consider a different diamond shape. 

People often confuse carat weight with the actual carat size of the diamond. As the carat weight increases, the size of the diamond does to, as long as it's the same shape. The following diamond shapes are all one carat, but appear different sizes.

The other thing to remember about diamond carat weight is that as the weight increases, the other three Cs of diamond quality have to increase too. This is why a two 1 carat diamonds are going to cost less than a 2 carat center diamond. 

Mining an eye-clean diamond is hard work. The truth is, only about 20% of diamonds mined are actually gem quality. Miners sifts through 250 tons of ore in order to find rough diamonds that are clear to the naked eye.

On average, they find a 1 carat  eye-clean diamond per 250 tons of diamond ore. This is why diamonds cost so much, because they are rare to find. 

Read Also: What are eye-clean diamonds?

So, if it's that difficult to mine a 1 carat diamond, how much more difficult do you think it is to find a high quality 2 carat diamond? And the cost of it? It will most definitely be more than twice the cost of a 1 carat.

While we can't avoid the increase priced, there's a way to at least get a better deal. When you're shopping at a major retailer, you'll usually find carat weight of a center diamond measured as 1/3, 1/4, 1/2, 3/4, 1, 1 1/2, and 2. Nice whole numbers. 

Carat weight is not only measured in this way, but it carat points. There are 100pts in a 1 carat round diamond. While you won't see carat points mentioned too often in a sales pitch, you'll most definitely be able to find loose diamonds measured in carat points online at jewelers like James Allen and Blue Nile. 

Instead of using whole numbers like the jewelry retailers, using carat points can save you a bit of cash. Choose  a .92 carat point diamond instead of a 1 carat. The visible difference is unnoticeable, but the price is different.

Check out the price difference between a .92 round brilliant diamond with the same diamond grades as a 1 carat diamond from James Allen.

.92 round brilliant diamond


1 carat round brilliant diamond


Round Cut vs Other Diamond Cuts

Round vs Princess Cut

round cut 14k white gold diamond engagement ring

Round Cut

princess cut 14k white gold diamond engagement ring

Princess Cut

Round vs Princess Cut

Which is more durable?

Princess cut diamonds are the second most popular diamond shape, right after the round. Some customers prefer something a little more unique than the traditional round. But, princess cut diamonds are a little more fragile. While diamonds are the hardest mineral known to man, it is still possible for them to chip, crack, or break. If you hit anything a the right spot with the right amount of pressure, it can break. 

Furthermore, a princess cut diamond and other fancy shape diamonds have pointed corners that are more vulnerable to damage. This is something to especially be aware of in a solitaire setting. A round cut diamond can still chip on its girdle, but having a rounded edge makes it less likely to happen than a princess cut. 

Click To Learn More About The Princess Cut Diamond Shape

Which is more versatile?

The choice of diamond shape with any ring setting or style is completely up to personal preference, there is a consumer market that prefers princess cut diamonds as center stones for certain settings and not others. This because the square shape of the princess creates bold, geometric lines suitable for modern settings. Princess cut diamonds thrive with channel set diamonds where as rounds do not. 

Round cut diamonds pretty much look great in any kind of setting. They aren't often placed with channel-set diamonds, but with almost every other setting. A princess cut diamond doesn't look good in a bezel setting either. But a solitaire, vintage style, and even a tension setting will look beautiful with a round cut diamond.

Round Cut vs Cushion Cut

Cushion cut diamonds are basically a cross between a round and a princess. They are the third most popular diamond shape. 

Round Cut 14k Yellow Gold Engagement Ring

Round Cut

Cushion Cut 14k Yellow Gold Engagement Ring

Cushion Cut

Which Sparkles More?

A round cut diamond is the epitome of all diamonds when it comes to brilliance. No diamond shape will have a the sparkle and fire like a round stone does, even if it is a brilliant cut shape.

A cushion cut diamond can come close and so can a princess cut. But because of  round cut diamonds' ideal proportions and exact symmetry standard, neither of these diamond shapes are able to be cut to that standard. 

Which is a better cut diamond?

It's hard to say. We know round cuts sparkle better, but are they better than cushion cut diamonds? You can find a fantastic cushion cut, but it takes more work. Shopping for a round diamond is a whole lot easier when it comes to cut quality.

You know that you need an Excellent cut or an ideal cut, and you are getting the best of what round diamonds have to offer in cut quality.  But with a cushion cut, the guidelines on picking out the best quality are not definite.

There's a range of crown size, pavilion depths, and other proportion measurements that are said to be good diamonds. But there is no set standard.

Where To Buy The Best Round Cut Diamond?

It's no secret that you can find round cut diamonds everywhere you look for fine jewelry, but where is the best place to buy a high quality round diamond? Is it in-store at mega retailer like Jared, or perhaps a local family owned business. Maybe even a local custom jeweler. But let me do you one better. 

James Allen is an online jewelry store that dedicates itself to letting you be in control of the craftsmanship of your engagement ring. You can choose from their library of thousands of loose diamonds as well as lab-created and fancy colored.

Each stone in the library has 360 viewing technology at high magnification to help ease any apprehension you might feel about purchasing online. Buying anything online used to be taboo, and now for a lot of us, it's become a preference. So why not diamonds and bridal jewelry?

When you buy a round cut diamond from James Allen, you are saying yes to a pleasant and pressure-free experience as you take all the time you need to buy with confidence.

After all, you should 100% love the piece you've put together. And even if you don't know much about diamonds, James Allen's staff is there 24/7 to answer all of your questions. They have GIA trained gemologists and diamond experts that can go over grading reports and any of your in-depth questions. 

Best of all, the staff doesn't make any commission off of your purchase, so there is no biased information trying to tip you towards a purchase. 100% unbiased information.

James Allen also offers their customers one free ring resizing should your ordered ring not fit, as well as a free lifetime warranty. The warranty covers all routing work done on a ring like rhodium plating white gold, retipping prongs, or tightening stones. At mega retailers, you generally have to pay for a lifetime warranty that can be a couple hundred dollars. 

If I can't convince you to purchase online, I do recommend that you see a local jeweler or family jewelry store as I'll always encourage you to help your community. Just stay away from mega retailers that often sell lower quality diamonds for higher prices with untrained staff behind them. 

360 diamond display technology

What Are The Best Settings For Round Cut Diamonds?

Round diamonds can really go into any ring setting of any style. But, there are also different advantages and disadvantages when selecting a ring setting or style. Some settings will maximize brilliance like a tension setting, while others might impact brilliance such as a bezel setting. Here are some of our favorite setting for round cut diamonds. 

  1. Heirloom Petite Milgrain Engagement Ring
  2. 14K Rose Gold Twisted Pave Engagement Ring
  3. 14K White Gold Pave Wave Engagement Ring
  4. Monique Lhuillier Floral Marquise Diamond Engagement Ring
  5. 14K Gold Two-Tone Modern Twisted Solitaire Engagement Ring

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