Round Brilliant Cut Diamonds [In-Depth Guide]

Round Brilliant Cut Diamonds [In-Depth Guide]

Round Brilliant Cut Diamonds [In-Depth Guide]

Posted by Sharif Khan on 19th Nov 2022

Round Brilliant Cut Diamonds

round cut diamonds

Round Brilliant Cut Diamonds Summary

Popularity Round diamonds are the most popular among the diamond shapes. On account of its brilliance, it is often recognized as a symbol of the diamond trade itself.
Cut A total depth of 59-62.5% and a total table of 53%-58.5% is preferred in round brilliant cut diamonds. Please see the chart below for detailed information and analysis.
Fluorescence Although, oftentimes a negative factor, but it can be helpful in some cases. See more below.
Certification GIA and AGS are the best grading labs. Buy a diamond that is graded by one of these two labs.
Color While D to F are top color grades, we also recommend G color. Additionally, H and I are amazing budget color options to consider.
Clarity Preferably, flawless to VSS/VS1 clarity ranges are great, but VS2 is also safe. SI1/SI2 are good budget options. When considering SI2 clarity diamonds, carefully review the clarity characteristics and location of inclusions to determine if the stone is eye clean.
Balancing 4Cs If budget is not a primary concern, look for a round diamond that has specs like this one (option 1). Conversely, if a nice quality large stone is desired within a good budget range, specs like these are what we would recommend (option 2). If the budget is tight and the goal is to buy a big stone with decent gem quality, buy something like this (option 3). If, however, you are on the lookout for something cheaper, consider compromising on color while maximizing on clarity and cut (option 4)

James Allen

What Are Round Brilliant Cut Diamonds?

Round cut, also known as round brilliant cut, diamonds make up roughly 70-80% of all globally traded polished diamonds. Due to progress in research and the development of a standard grading methodology, round diamonds are now treated as a commodity. As a result, their prices are becoming increasingly competitive with minimal margins.

The Gemological Institute of America (GIA) introduced the standard cut grading system for "unmodified" round brilliant-cut diamonds in 2005. According to the institute, for a round diamond to qualify as an unmodified round brilliant cut diamond, it must have 58 facets and be cut according to modern industry standards. The American Gems Society (AGS), on the other hand, uses a proportion-based grading system.

The diamond trade has evolved significantly over the last decade. Due to the internet and the abundance of online information, first-time buyers are no longer at the mercy of local retailers to purchase a high-quality diamond at a reasonable price. Instead, they can easily review diamond prices online on different websites and determine a competitive price within a given range.

For example, it is not hard to determine the price of a round-cut 2-carat diamond with VS1 clarity, G color, excellent cut, and no fluorescence graded by GIA or AGS . Buyers can check prices at James Allen here and Brilliant Earth here and know what a reasonable price is for the specified 2-carat diamond.

Finally, lab-grown diamonds are becoming more popular and could be good budget alternatives to mined ones.

What to Avoid in Round Diamonds?

While we thoroughly cover the 4Cs and additional vital factors related to round diamonds below, here are the three red flags that should not be ignored in a round-cut diamond:

  • Do not compromise on the cut quality when it comes to round diamonds. Cutters have many tricks up their sleeves and will do anything to save more of the original rough diamond. Our proportions chart below will be your best guard against such temptations.
  • Do not buy a round diamond whose clarity grade is based on clouds. Such diamonds are dull and do not emit any brilliance. Read the comment section on a GIA report to determine if the clarity grade is assigned based on clouds. This is different from having clouds as inclusions, which is not a significant issue.
  • Avoid strong blue fluorescence, especially in D-to-G color round diamonds. In most cases, strong blue fluorescence affects high-color grade diamonds very negatively.

Analyzing the Cut in Round Brilliant Diamonds

When it comes to the cut of round diamonds, many marketers use taglines like "heart & arrows," "hearts on fire," "a cut above," and so forth for their round cut diamonds. But the benchmarks and methods for cutting a round brilliant cut diamond are more or less similar. As long as a buyer abides by the guidelines listed below, they should be able to determine what a well-cut round diamond is and how it looks regardless of its brand name.

Tip: James Allen also has the best cutting-edge 40X 360°HD technology that you can use to compare the cut of a diamond based on the proportions below. It will also help you assess diamond clarity to locate the location of inclusions and determine if they are bad black crystals. In addition, their filter is user-friendly and does not cost anything. Via this feature, thousands of diamonds can be viewed in 3D 360-degree.

Depth %

 Poor/Fair: <56/>65%

 Good: 57.6-58/63.4-64.5

 Very Good: 58-59/62.8-63.3

 Excellent: 59-62.6

Table %

 Poor/Fair:<50/>68.5>

 Good:51-52/62-64

 Very Good: 51-52/59-62

 Excellent:53-58.5


 Poor/Fair: Medium

 Good: Small

 Very Good: None/Very Small

 Excellent: None

Crown Angle

 Poor/Fair:<28.5/>38.5

 Good: 30-32/36-38

 Very Good: 32-34/35-36

 Excellent: 34-35

Pavilion Angle

 Poor/Fair: <39/>46

 Good: 41-42/44-45.3

 Very Good: 41.3-42.6/43.3-43.8

 Excellent: 40-41.2


 Poor/Fair: Ex. Thin – Ex. Thick

 Good: Very thin - thick

 Very Good: Very thin - slightly thick

 Excellent: Thin - slightly thick

Round Cut Diamond Scale

58 Facets Round Cut Diamond Illustration by GIA. Copyrights: GIA

For additional insights, please read our article on why diamond cut is important. In this article, we explain that while the cut carries immense significance, if budget is an issue, you have the latitude of going as low as very good if the stone is not too deeply cut—in which case it would look very small—or overly shallow—in which case it will look dull and have no fire and brilliance.

Here is an example of a very good-cut diamond that resembles an excellently cut one. If you can find a diamond like this, there is no need to worry about it being graded as an "excellent cut" on a GIA grading report. 

Excellent vs Super Ideal Proportions

The chart above can prove decisive in distinguishing a super ideal cut diamond from an ideal or excellent cut stone when comparing two diamonds graded as excellent cut by GIA. Besides, pay attention to the crown, pavilion angles, and girdle size. Apart from the obvious quality of the depth and table, each factor is responsible for the slight difference in cut.

Analyzing Color in Round Brilliant Cut Diamonds

Round Diamond Color Sclae

Color is the second most important C after the cut in round-cut diamonds. In white diamonds, it ranges from colorless (D-F) and near-colorless (G-J) to Z, all of which are faint, light, and faint yellow. While colorless diamonds are always preferred by people who can afford them, G/H color diamonds can still be amazing options. If you want to buy an H or I-color diamond, please remember faint to medium blue fluorescence can be helpful as blue complements yellow and can help make a diamond look whiter. Check out our diamond color scale and chart for additional details.

Hint: If you find yourself at a standstill where you must choose between a VVS1 clarity H color or a VS1 clarity G color diamond, go for the latter (VS1 G) — all other factors being equal.

Analyzing Clarity in Round Brilliant Cut Diamonds

The GIA grades diamond clarity from flawless to I3, with 3 FL being the highest and I3 being the lowest. Avoiding visible inclusions is vital for a diamond's overall appearance and brilliance. Clarity is one of the most technical Cs in a diamond.

What types of inclusions are safe, and what should be avoided?

In a nutshell, avoid big black crystals and ascertain that the inclusions are not on the table of the diamond. Additionally, determine that inclusions are small and spread across the stone: it is essential so that the inclusions do not remain visible to the naked eye. Finally, see to it that the clarity grade of the diamond is not based on clouds.

While not necessarily bad inclusions, if a stone's clarity grade relies solely on clouds, it can get hazy and oily and carry no sparkle. 

Round Diamond Clarity Chart

Prioritizing the 4Cs in Round Brilliant Cut Diamonds

To get the best diamond within a given budget range, one of the most challenging questions shoppers often struggle to address is whether and how to compromise on the 4Cs of a diamond—carat weight, cut, clarity, and color. To help answer this question, consider the following four scenarios before making a final decision:

  1. Investment grade (highest quality and rare): Buyers prioritize flawless/VVS and colorless (D-E) diamonds with ideal proportions, GIA and AGS certification, and no fluorescence under this category.
  2. High-quality big diamonds (great value): In this range, a buyer looks for a VS2/VS1 and G/H color diamond with none, faint fluorescence, and excellent to very good cut grades. The goal is to get the biggest bang for the buck without compromising quality.
  3. Getting the biggest yet most beautiful diamond (a balanced approach): In this scenario, shoppers try to find the most prominent stone possible without totally ignoring quality. So, given that they want a big diamond, they aim for a carat weight of 1.5 carats instead of 1 carat. For example, they would buy a 1.5 carat round diamond with SI1 clarity, I color, medium blue fluorescence, and a very good cut instead of a 1 carat E VVS1 clarity diamond.
  4. Getting the largest stone possible (a tight budget): A buyer mainly focuses on the size of the diamond and how much it shines and does not mind some visible inclusions or the yellow tint if the stone is affordable. They may buy a 2-3 carat K-M color diamond with inclusions being non-black carbon crystals such as feathers towards the girdle, strong blue fluorescence to aid the color, and a very good to excellent cut for optimal brilliance and fire.

Additionally, here are our suggested options for buyers with budget constraints:

Excellent purchase

  • At least 1.0 carats in weight
  • Very good or excellent cut with very good to excellent polish and symmetry
  • G or above in color
  • Clarity of SI1 or higher
  • No/faint fluorescence

Very Good purchase

  • At least 0.90 carats in weight
  • Very good cut with good to excellent polish and symmetry and very good proportions.
  • H or above in color
  • Clarity of SI2 or higher
  • No, faint, or medium blue fluorescence

Good purchase

  • At least 0.80 carats in weight
  • Good cut with good to very good polish and symmetry with good proportions.
  • I or above in color
  • Clarity of SI2 or higher
  • None, Faint or medium blue fluorescence

Buying Round Brilliant Cut Diamonds Online

Though the trade has improved significantly, and it is safer now to buy diamonds online, a buyer should consider certain crucial factors. For example, the seller should offer a solid return, lifetime warranty, and upgrade policies. These factors and other relevant insights are outlined in our article on the best places to buy diamonds for your reference.

A brand's reputation also carries immense importance because of quality assurance concerns and the long-term support they provide. It may be worth the money to pay an extra 5%, but you should buy at a place that offers free repairs when a stone falls off the mounting and/or when you need to resize the ring.

Round Brilliant vs. Old European Cuts

In today's marketplace, roughly 75-80% of all the diamonds sold are round-shaped. Since 1750, round diamonds have witnessed many changes, especially in the variation of facet size and proportions. New changes are being made to a cut's table size, total depth, culet size, crown height, and length of the lower half facets. Nonetheless, diamonds from every era have had distinctive and discrete appearances.

Most consumers choose round brilliant-cut diamonds because they meet their modern conception of aesthetics. Round brilliant-cut diamonds have a tight mosaic of light and carry dark patterns with longer lower half facets that gemologists term "splintery."

The older cuts, like the old European one, on the other hand, have a small table, a large culet, a steep crown, and shorter lower half facets, which gives them a "blocky" or "checkerboard" pattern. Notably, despite their beauty, judging them against modern round brilliant-cut diamonds is not practical due to differences in their proportions.

The Gemological Institute of America introduced the cut grading system for unmodified round brilliant cut diamonds. To distinguish between the older style of brilliant-cut diamonds and those now in vogue, the term "unmodified round brilliant" is used for a symmetrical round-cut diamond with 58 facets and cut according to modern standards.

GIA uses five cut grades, including excellent, very good, good, fair, and poor, to determine the cut of a round cut diamond. On the other hand, AGS uses six cut grades by adding the "ideal cut" to the equilibrium.

Key differences between old European and modern round brilliant cut diamonds

According to GIA, old European cuts have the following specifications:

  1. Lower half facet length: less than or equal to 60 percent
  2. Table size: less than or equal to 53 percent
  3. Crown angle: greater than or equal to 40 percent
  4. Culet size: slightly large

Moreover, the 58-facet round brilliant cuts have to meet the following requirements to be called brilliant modern cuts:

  1. Lower half length: less than or equal to 60 percent
  2. Culet size: medium or a slight bit larger
  3. Star length: less than or equal to 60 percent.

Old European vs Round Cut

The image above is a good side-by-side comparison of the two different round diamond cuts. Notice that the European cut has a smaller table, a larger culet, and shorter lower-half facets than the brilliant round cut, which has a larger table, smaller culet, and longer lower-half facets.

Buy Super Ideal Cut AGS Certified Round Diamond ( Link)

Round  Brillaint Cut Diamonds FAQs

What is a round-shaped diamond?

As stated before, round diamonds are the most popular diamond shape. Because they have a large surface area, they are generally more expensive than fancy-cut stones. A bigger rough diamond is needed to cut a 1-carat round brilliant-cut diamond instead of a 1-carat princess-cut diamond.

What are the ideal proportions for a round-cut diamond?

Please carefully read and follow our diamond proportion chart and guide to help you figure out the best round diamond proportions.

What should I prioritize in terms of the 4Cs while buying a diamond?

The four scenarios we discussed should help you think about the 4Cs when looking for a round diamond.

What are the most reliable diamond certifications?

As mentioned above, GIA and AGS are the best diamond grading labs in the world.

How does fluorescence affect a diamond?

To understand the issue of fluorescence, carefully review our in-depth article on the subject. It is an important topic as it can be either a negative or positive factor depending on the stone's color.

What is a good alternative shape to round diamonds?

In our opinion, an oval-cut diamond would be an excellent alternative to round-cut diamonds because of their similarities.

Is it safe to buy diamonds online?

Yes, trading diamonds online is very safe now. We now have a standard grading system that makes buying a diamond online easier.

Round Brilliants Cut Diamonds