Do Not Ignore 3 Flaws in Round Diamonds (In Depth Guide)

Do Not Ignore 3 Flaws in Round Diamonds (In Depth Guide)

Do Not Ignore 3 Flaws in Round Diamonds (In Depth Guide)

Posted by Sharif Khan on 24th Dec 2020

Round Cut Diamonds

While we will thoroughly cover the 4Cs and additional important factors related to round brilliant cut diamonds below, here are the three flaws that you should never compromise on when it comes to round diamonds:

  • Never ever 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 tricks.
  • Do not buy a round diamond the clarity grade of which is based on clouds. Such diamonds are dull and do not emit any brilliance. Read the comment section on a GIA report to find out if the clarity grade was assigned based on cloud (this is different from having clouds as inclusions, that is not a major issue).
  • Avoid strong blue fluorescence, especially in D to G color round diamonds. Strong or very strong blue fluorescence in most cases affects high color grade diamonds very negatively. 

James Allen

 Key Takeaways:

  1. The Round Cut Diamond is the most popular among the diamond shapes the world has thus far seen; so much so that on account of its brilliance, it's often recognized as a symbol of the diamond trade itself.
  2. In terms of 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!
  3. Fluorescence is, although, oftentimes a negative factor, but it can be helpful in some cases. See more below.
  4. GIA and AGS are the best grading labs; please buy a diamond that is graded by one of the two labs.
  5. As for the color, while D to F are top color grades, we also recommend G color. Also, H and I are amazing budget color options to consider.
  6. Preferably, flawless to VSS/VS1 clarity ranges are great, but VS2 is also safe. SI1/SI2 are good budget options, and so while contemplating buying it, please carefully review the clarity characteristics and location of inclusions in SI1/SI2 to determine if the stone is eye clean.
  7. 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 decent quality stone, buy something like this (option 3). If, however, a buyer is on the lookout for something cheaper, he/she should consider compromising on color while maximizing on clarity and cut (option 4).

ideal round cut chart


Round brilliant cut diamonds make up the lion’s share—roughly 70-80%—of all polished diamonds traded around the world. Thanks to the unparalleled progress in research and the development of a standard method for grading diamonds, round diamonds have been commodified whilst their prices are increasingly becoming a source of very small margins for markups by retailers.

The Gemological Institute of America (GIA) introduced the standard cut grading system for "unmodified" round brilliant cut diamonds in 2005. Per the GIA, in order for a round diamond to qualify as an unmodified round brilliant cut diamond, it needs to have 58 facets and be cut according to the modern standards rampant in the industry. 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. Owing to the internet—and the abundance of the information therein—and the GIA, those interested in buying diamonds are no longer at the mercy of local retailers who sell them each at a 150-200% markup. You can easily review diamond prices online on as many websites as you so desire, and, subsequently, acquire the required understanding about what a competitive price might be for any given range, say, for a Round Cut 2ct., VS1, G Color, or an Excellent Cut with no fluorescence graded by the GIA or the AGS.

Analyzing the Cut:

When it comes to the cut, it is a common observation in the field that while many marketers use taglines like "heart & arrows", "hearts on fire", "a cut above", and so forth for their round cut diamonds, the benchmarks and methods for cutting a round brilliant cut diamond are more or less the same. Also, for as long as you abide by the guidelines listed below, you 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 take to as a tool for comparing the cut of a diamond based on the proportions below, for assessing diamond clarity to locate the location of inclusions, and for a thorough evaluation to determine if they are bad black crystals. Their filter is user-friendly and doesn't cost anything. Via this feature, thousands of diamonds can be viewed in a 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

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

If you find the cut issue a troublesome matter, please review our article on is the diamond cut important?! In this article, we explain that while the cut carries immense significance, but if budget is an issue, you have the latitude of going as low as very good or good cut for as long as you are ensuring that the stone is not either too deeply cut—in which case it would look very small—or is overly shallow—in which case it won't have the flare that one may want to see in a diamond.

Here is an example of a very good cut diamond that is as good as an excellent cut diamond, and if you are able to find something like this, you need not to worry about it not being graded as "excellent”. Also, please know that sometimes it depends only on the opinion of the gemologist grading it.

round cut diamond very good cut

Excellent vs Super Ideal Cut:

The chart above can prove decisive in determining a super ideal cut diamond over an ideal or excellent cut one while comparing two diamonds both of which obtained an excellent cut from the GIA. Pay earnest attention to the crown and pavilion angles and the girdle size. Each one of these measures, besides the obvious quality of the depth and table, is responsible for such differences as may otherwise not be decipherable for the layman.

Video explanation on how to analyze the cut of a Round Cut Diamond:

In the said video, Sharif provides an in-depth explanation of the different aspects of round cut diamonds. Notwithstanding that it is a lengthy video, it is wholly worth your time given that analyzing the cut of a round diamond can be a challenging task.

Prioritizing 4Cs:

One of the hardest questions that shoppers often confront adheres to how ought to compare round diamonds and which C of the 4 Cs—carat weight, cut, clarity, and color—they should compromise on in order to get the best diamond within budget. Please watch the video below where we explain four scenarios that would help you decide which approach is best for you within your budget!

These four circumstances include:

1 – Investment grade per us: high quality and rare

We believe that flawless, colorless D, super ideal proportions, and GIA graded diamonds with no fluorescence will be the highest reference point for, and the primary driving force behind the decision-making of, the buyer in each carat range.

2 – What we consider investment-grade and best option: high quality and circulation

In the said range, we take into account circulation and quality. A buyer in this range would be looking for a VS2/VS1 and G/H color diamond with faint/medium blue fluorescence or preferably none and excellent to very good cut grades. The buyer's goal here has to be to get the biggest bang for their buck but, at the same time, not to overly compromise on quality.

3 – Getting the biggest yet beautiful diamond: a balanced approach

In such a scenario, shoppers are on the lookout for the biggest stone available without letting the latter’s quality be compromised a great deal. Because they want the stone to sparkle despite the size, they opt for as low as H/I color diamond knowing that sacrificing on the clarity and fluorescence of their purchase is inevitable and aim for the carat range of 1.5 instead of 1. If I were the shopper, I would prefer laying my hands upon a 1.5 carat round diamond with SI1 clarity, I color, medium/strong blue reference, and carrying a very good cut over an E 1ct. VVS1—implying that I would still aim at maintaining some level of quality while going for a big stone.

4 – Getting the largest stone possible within a tight budget:

Given the situation, the buyer mainly focuses on the size of the diamond and how much it shines and doesn't mind some visible inclusions or the yellow tint of the diamonds that fall within the lower price range. Resultantly, they would go for a 2-3 carat J/K color diamond of the SI2 range with inclusions being non-black carbon crystals such as feathers towards the girdle, strong blue fluorescence to aid the color, and very good to excellent cut for optimal brilliance and fire.

Analyzing the color issue:

Color is the second most important C after the cut in the very process of the assessment of round cut diamonds.  Diamond color that ranges from colorless (D-F), near colorless (G-J), and from then onwards to Z are considered faint, light, and faint yellow. While colorless diamonds are always preferred for people who can afford them, G/H color diamonds can still be enchanting. If you happen to buy an H or I color diamond, faint to medium blue fluorescence would be helpful as it is a color that compliments blue and can help make your diamond look whiter.

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

Diamond color scale

Analyzing the issue of clarity:

GIA grades diamond clarity from flawless to included 3 - FL to I3. Those having experience in this field know that people avoid visible inclusions in their diamonds knowing that it can affect their overall appearance and the brilliance they ought to ideally possess. Therefore, before you take a step further, make sure you are familiar with the settled importance of diamond clarity.

Clarity is one of the most technical Cs in a diamond. What kind of inclusions are good and what otherwise? What should you avoid?

Avoid big black crystals and ensure that the inclusions are not on the table of the stone in the center. Also, see to it that the inclusions found in a stone are small and are spanned across the stone so that the possibility of their being visible to the naked eye isn’t obvious. Finally, make sure that the clarity grade is not based on clouds; for although clouds are not necessarily bad inclusions, if a stone's clarity grade is solely based upon them, it means that it is replete with them, hence hazy and oily and carrying no sparkle at all. 

GIA Diamond Clarity Chart

Important Points to Consider While Shopping for a Diamond:

Notwithstanding the fact that the trade has improved significantly thereby making it relatively safer now to buy diamonds online, it is still preferable to shop at a reputable store to be on the safer side. Whilst buying, make sure that you are offered a solid return policy, lifetime warranty, and lifetime upgrade policy. Two such reliable sites that, per us, stand out are James Allen for GIA graded diamonds and for ideal AGS graded diamonds: we would highly recommend that you buy a stone that is graded by either GIA or AGS.

The reputation of a brand carries immense importance because the market is fraught with people hell-bent upon selling inferior, cheap stones at a higher price. Amid such times, we recommend that you pay 5% more by buying at a place that will support you when a stone falls off your mounting or when you need to resize your ring in lieu of buying at an online store: some of the new sites might not be around next year, but they will confidently promise you a life-time warranty.

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
  • SI1 or above in clarity
  • 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
  • SI2 or above in clarity
  • 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
  • SI2 or above in clarity
  • None, faint or medium blue fluorescence

Additional background:

In today’s marketplace, roughly 75-80% of all the diamonds sold are round shaped available in innumerable varieties, but the most common ones usually have 57 to 58 facets. Since 1750, diamonds have witnessed a plethora of changes especially in the variation of facet size and proportions. New styles and changes are being made in particular in the diamonds’ 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 tend to 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, say, the old European cut, on the other hand, has a small table, large culet, steep crown, and shorter lower half facets which gives them a “blocky” or “checkerboard” pattern. It is necessary to add here that 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. In order to distinguish between the older style brilliant-cut diamonds and the ones now in vogue, the term “unmodified round brilliant” is used for a symmetrical round cut diamond that has 58 facets and is cut according to the modern standards.

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

Below are some of the 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 modern brilliant 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.

European Vs Modern 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, larger culet, and shorter lower-half facets as opposed to the round brilliant cut that has a larger table, smaller culet, and longer lower-half facets.

Below is an illustration of an AGS ideal round brilliant cut diamond:

AGS Ideal Round Cut Diamond

To conclude, below is a summary of the top questions we have tried to answer in this article:

What is a round shape diamond?

As contended before, round diamonds are the most popular among the available diamonds bearing different shapes. Please note that because round diamonds generally have a large surface size, they are generally more expensive than fancy-cut stones. You would need a bigger, rough diamond to cut it into a 1 carat round brilliant cut diamond. It is solely for this reason that round-shape diamonds are generally pricier than others.

What are the ideal proportions for a round cut diamond?

Please carefully review and follow our diamond proportion chart and guide for reference in order to better make sense of the evaluation process of the cut of round cut diamonds!

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

The aforementioned four scenarios that we have explained should be very helpful in terms of prioritizing the 4Cs while contemplating buying a round diamond.

What are reliable diamond certifications?

As stated above, the GIA and the AGS are the best diamond testing labs in the world: GIA, according to us, is the king.

How does fluorescence affect a diamond?

In order to best understand the logic around fluorescence, please carefully review our guide pertaining to the same subject. We believe that it is an important topic to be familiar with as it can be both a negative and positive factor depending on the color of the stone.

What is a good alternative shape to round diamonds?

In our opinion, an oval cut diamond would be a good alternative to round cut diamonds given that the former category of diamonds has become very popular of late.

Is it safe to buy diamonds online?

Yes, the diamond trade has evolved significantly over the years. Thanks to the GIA, we now also have a standard grading system that makes buying a diamond online easier as compared to the days gone by. But while so doing, ascertain that you are buying a diamond that is graded either by GIA or AGS from a reliable website online.

Round Cut Diamond