How to Assess the Cut Quality of a Diamond

A diamond with a good cut will sparkle and show off beautiful brilliance. But, a badly cut diamond will not reflect light the same way, meaning that it will be dull and lifeless. Because the cut is so important in determining the stone’s overall beauty, the quality of the cut is essential to its value.

Since the cut of a diamond plays such a fundamental role in the overall appearance and value of the stone, it is often thought of as the most important of the 4Cs (color, clarity, carat, and cut). If you’re starting to shop for diamonds, you should be aware of how the diamond’s cut quality is determined so that you can get a beautiful diamond that is within your price range.

We’ll explain the relationship between a diamond’s value and the quality of its cut and how professionals assess quality. Plus, we’ll go over helpful tips for you to buy a diamond with good cut quality.

How Does Cut Determine Value and Quality?

The cut of a diamond affects its overall quality and, by extension, its value. A well-cut diamond will reflect light back to your eye, showing off sparkle and brilliance, which is a big determinant of a stone’s overall beauty. Since beauty is a big factor when it comes to value, diamonds with a good cut are highly in-demand and garner a higher price.

Symmetry and proportions are important factors in a diamond’s value. If the depth of a diamond is too deep or shallow, then the light will escape through it. A well-cut diamond will not be too deep or too shallow, allowing light to reflect back to the viewer. Additionally, the proportions have to be incredibly precise in order to reflect light to its full potential. If a diamond’s proportions or symmetry are off even by a little bit, it will negatively affect its brilliance.

A diamond cutter will evaluate the best shape for a particular rough diamond to yield the greatest profits.  Specific diamond-cut shapes have varying levels of brilliance, which will then affect the price.

Brilliant round-cut diamonds are the most popular types and are generally more expensive than other types. Fancy-shaped diamonds (every shape besides round) are less expensive and typically less brilliant than round cuts.

In terms of brilliance, princess-cut diamonds are next in line after the round cut. While the baguette and emerald shapes typically are the shapes with the least brilliance. Brilliance depends on your personal taste and ideas of beauty, so if you’re shopping for a diamond, you may prefer certain shapes over others because of their sparkle.

However, if you opt for a round diamond with a poor cut grade, it will not be as valuable as a fancy-shaped diamond with a good cut grade. So, understanding the cut grade is important as you shop for a diamond, as it will affect the value of the stone more than any other of the 4Cs. You can even go with lower grades of the other 4Cs if you have an excellent cut grade, as it won’t affect the overall beauty or the diamond quality.

How Are Diamond Cuts Assessed?

Diamond cuts are assessed by professionals and given a grade to indicate the overall diamond quality. A few of the factors that are taken into account are the proportions, symmetry, and finish (polish). These different factors all affect the brilliance, fire, and scintillation of the diamond.


The diamond’s proportions are important to its overall cut grade. The crown, pavilion, and facets all play a role in the diamond’s appearance. Though the proportions are important to the overall beauty of the stone, there is no single set of proportions that performs the best. This information means that an excellently cut diamond can have different proportions from another excellently cut diamond, and their light performance still has a similar effect on the viewer.

The crown of the diamond is the part of the stone that extends up to the table (the top facet of the stone) down to the girdle (the widest part of the stone). The crown will be made up of facets cut into a brilliant or step style. Facets that are cut into step styles will have less fire and scintillation compared to brilliant cut facets.

The pavilion is the part of the diamond that extends from the girdle to the culet (bottom facet or point). Though it’s the bottom half of the diamond, the pavilion plays a fundamental role in the light-reflecting performance of the stone. A pavilion that is too deep or too shallow will allow light to escape from the bottom or sides of the stone instead of reflecting light back through the top towards the viewer. In order to get the maximum amount of sparkle, a diamond’s pavilion must be carefully crafted with the right proportions in mind.

The facets of the diamond should also be taken into consideration. Too many facets or not enough facets can affect the brilliance of the diamond. However, facets that are correctly proportioned, placed, and sized will have great light-reflecting properties. It’s important for the facets to be precisely cut, as a small degree of difference can mean a poorer cut grade.


The symmetry of a diamond refers to the positioning and balance of facets within the stone. A diamond’s symmetry is judged by the facet’s size and shape and the alignment and placement of the crown, pavilion, culet, and table.

Diamond cutters will evaluate the rough diamond to determine the best course of action for a particular diamond. Though symmetry is the ideal goal, some diamonds may be slightly asymmetrical in order to hide inclusions or keep carat weight.

Although finding tiny flaws in a diamond is difficult without a magnifying lens, you’ll be able to tell if a diamond has poor symmetry by its light-reflecting performance. The angles and facets are quintessential in directing light through the diamond, so disproportional facets with poor symmetry will not be brilliant or sparkling.

Symmetry is also important for more creative shapes, like the pear shape or the heart shape. With fancy-shaped diamonds, the shape is essential for the finished diamond’s overall appearance. If the diamond is asymmetrical, then the stone will be noticeably off and won’t look right.

Finish (Polish)

The polish of the finished diamond refers to how the diamond cutter finished the stone to achieve a glass-like appearance. Nearly all diamonds have some degree of polish flaws. However, most of these flaws can only be seen under intense magnification, not by the naked eye.

And unlike inclusions, whose flaws happen during the natural diamond forming process, flaws in the polish are the consequence of human error. Some of the possible polish marks a gemologist might find on a finished diamond include scratches, abrasions, nicks, bumpy textures, and an unpolished girdle.

It’s fairly unlikely that you’ll encounter a visible polish mark while browsing in a jewelry store. Though even if you did find a mark, it won’t affect the stone’s overall fire or brilliance.

What Is the Cut Grading Scale?

A diamond’s cut is graded on a scale from poor, fair, good, very good, and excellent. In order to judge a diamond and give it a grade, gemologists will evaluate the stone’s performance in the following areas

  • Brightness: the way the white light reflects from the diamond
  • Fire: colorful rainbow flashes while under a light
  • Scintillation: the contrasting light and dark colors within the diamond
  • Weight Ratio: the stone’s weight in relation to its diameter
  • Durability: the thickness of its girdle
  • Polish: the number of marks the diamond cutter left in the finished stone
  • Symmetry: the arrangement of the diamond’s facets and angles.

With so many variables in play when grading the cut quality of a diamond, this part of the stone is often challenging to assess. But the quality of the cut indicates the overall beauty of the stone, so opting for an excellent or very good cut will mean that you get a gorgeous stone. You may even go for lower grades in clarity and color or a lower carat weight without sacrificing beauty or value when you have an excellent cut.

How Can You Visually Inspect a Diamond Without a Magnifying Lense?

As you’re shopping for diamond rings, you’ll want to visually inspect all diamonds because written measurements, proportions, and grades can not tell you the whole story. Some diamonds have the same or similar measurements and proportions but look very different.

One of the most important ways to visually inspect a diamond is to evaluate its light reflection properties. You’ll want to see how the diamond performs in different lighting conditions. While a diamond may seem super sparkling under the bright jewelry store lights, it may not look the same in normal daylight conditions. Also, depending on your personal preferences and taste, you may prefer less sparkle in diamond rings, so you’ll need to look out for the level of fire.

Another way to determine its light-reflecting capabilities is to take a look at its overall depth. A diamond that is especially long and deep will not reflect light well. In addition, a shallow depth will also not reflect light well. You should try to go with a diamond that is somewhere between deep and shallow cuts for the best brightness.

If you’re browsing through fancy-shaped diamond rings, then you’ll want to make sure that you see up-close photos of the diamond from various angles. For fancy-shaped diamonds, symmetry is incredibly important to the overall shape. So, if you’re interested in purchasing a heart-shaped diamond, if you aren’t able to see it in person, you should definitely look closely at the photos to ensure that it’s symmetrical.

You should also be on the lookout for noticeable dark marks. These might be inclusions or, more rarely, polish marks. While a single mark is only a small factor in the overall cut, if there are a few noticeable marks to the eye, then that diamond might not be the right choice for you.

What Are the Key Tips for Choosing a Diamond With a High-Quality Cut?

Choosing a diamond with a good quality cut is the most important aspect when shopping for diamond rings. A diamond with an excellent cut will be beautiful. If you are looking to save money by manipulating the 4Cs, the cut quality is not the place to save money. If you’re looking for the best diamond, then you’ll want to opt for a good quality cut and choose lower grades in color or clarity.

It’s a good idea to shop with reputable jewelry dealers to ensure that you’re buying a valuable and high-quality ring. If you can’t make it to the shop in person, then make sure that you carefully look at the photos to get a good sense of the diamond.

You should also have a good understanding of the grading scale and take a look at the diamond certificate. A respectable diamond organization will issue a certificate with the objective cut grade. This grade will help you to determine the overall diamond quality and value. The GIA and AGS issue diamond-grade certificates that you can trust.

Ultimately, picking out the perfect diamond ring can feel challenging. But when you understand the cut quality of a diamond, shopping can be a whole lot easier, as the cut quality is often the biggest deciding factor in the beauty of a diamond. For a gorgeous and high-quality diamond, opting for an excellent cut grade of a brilliant round diamond will ensure that you end up with an amazing ring. However, be sure to choose respectable jewelers and look carefully at the certificate while shopping. If you’re ready to start looking for the perfect diamond ring, our selection of diamonds only includes good-quality cut diamonds.