The Diamond Cut Guide: Most Popular Cuts & Grading Chart

The Diamond Cut Guide: Most Popular Cuts & Grading Chart

The Diamond Cut Guide: Most Popular Cuts & Grading Chart

Posted by Sharif Khan on 16th Jan 2021

diamond cut

The diamond cut is often acknowledged as the most important aspect when buying a diamond and hence should not be confused with the shape of the diamond. The cut refers to the brilliance of the diamond. In simple terms, the way a diamond is cut will determine how light is reflected through the stone.

A good cut will allow the light to travel through the stone and reflect from side to side. The light then reflects out of the stone, and this light/sparkle is what you see with your eye. In diamond terminology, this sparkle is "brilliance." 

Cutting diamonds to become jewelry is a delicate and highly regarded craft. It is both science and art - science in that certain angles must be precisely followed based on proportions and art in that the final shape must exude a high-class beauty. A diamond cut should not be confused with its shape which refers to the general outward appearance of a diamond.

The Cut of a Diamond is Important:

Diamond cut is perhaps the most important factor in assessing the overall brilliance and fire of a diamond. Because it is the only C that is not a natural element and is a human factor, it can be manipulated to save more rough while cutting a diamond. The Gemological Institute of America (GIA) has a developed a comprehensive system for assigning cut grades to round brilliant cut diamonds, but it has yet not finalized it for fancy shape diamonds such as a cushion or asscher cut diamond. The cut range is from Ideal/Excellent to Very Good, Good, Fair, and Poor. Since non-round shape diamonds do not have a cut grade in a GIA report, we recommend that you follow our guidelines for each diamond to determine how well the diamond is cut, for example, follow this guide for an  oval cut diamond. The most important factors to consider while assessing the cut of a diamond include the depth, table, girdle, crown angle, pavilion angle, and culet. You should especially pay attention to depth as it can be very large at times which can make a 1 carat diamond look like a 0.7ct. in person. Please follow our  diamond proportions guidelines for precise information on each shape.

James Allen

How GIA Cut Grade System Works:

The GIA Cut Grading System for brilliant round diamonds is defined and allocated one of 5 cut grades, which are: poor, fair, good, very good and excellent. The GIA system is based on a combination of predictive metrics, observation of the appearance of the diamonds, and computer modelling of diamond appearance. With the help of a prognostic computer model, the GIA system estimates the beauty and brilliance of diamonds based on interrelated specifications.

The GIA cut grading is based on the evaluation of seven elements. Three of the elements are based on appearance, and they include scintillation, brightness, and fire. The other four are based on craftsmanship and design. They include weight ratio, polish, durability, and symmetry.

Here is an outline that will assist you in understanding the GIA’s cut grading system and what differentiates an excellent from a good or fair cut.

Excellent grade: this category has high scintillation, brilliance and an even pattern of dark and light areas.

Very good: while this grade has high scintillation and brilliance, they are darker n the edges or the centre. Sometimes, a diamond can have a higher scintillation and brilliance, but the grade lowered by its pattern.

Good grade: this category is a bit dark and has lower scintillation. A diamond can be downgraded by its weight ratio or pattern.

Fair grade: a gem in this grade has little scintillation and brilliance.

Poor grade: gems in this grade have extremely poor proportions and display little scintillation or brilliance.

GIA cut diagram

Understanding the attributes of diamond appearance:

Here are some of the elements that make up a cut and how the component affect the appearance of the gem.


Polish is the quality level of diamond facets due to the polishing procedure or the blemishes made after the cutting procedure. Polish elements are situated on the surface and don’t visibly penetrate into gem as viewed at 10x magnification. Polish is evaluated on a scale comprising of excellent, very good, good, fair and poor. Most diamonds have imperfection since polish marks are brought by the craftsmanship mistakes. To lessen the mistakes, each facet of the diamond must be carefully polished at the end of the cutting procedure.

Perfectly-polished diamonds must have excellent smoothness and exceptional regularity such that it doesn’t have burn marks, nicks, wheel/polishing marks, lizard skin or abrasions. Nevertheless, the surface of the diamond is anisotropic, implying that there are harder and softer zones. For this reason, there are 14 dead spots at equally set-apart three-D areas that can cause the facet to be unpolishable. In most cases, the dead regions are situated at the cube and octahedral faces. To make sure the fire and brilliance of the gem are not affected, cutters must ensure that the facets do not coincide with the dead spots. The craftsman can move the facets, which will comprise the symmetry, to ensure that all facet will be polished.


Diamond symmetry is the alignment and appropriate positioning of its facets. A professional craftsman will put each facet in proper proportions that complement surrounding facets. The placement of the facet must be completed with professional precision since facet junction that doesn’t align will make the stone look uneven. Moreover, the symmetric quantity of a perfectly cut diamond will deter excessive carat weight in the profile. This makes the gem look right for its real weight.

Additionally, the alignment of facets will define the interaction of the stone with light. Some lights that hit the stone immediately reflects as a surface stare. A portion of the light that gets into the stone escapes via the bottom. The light won't have any visual impact on the viewer. A very shallow or deep cut will let light escape through the diamond’s internal wall or crown, making many facets appear dull or dark, and the general appearance will be less sparkly and brilliant. Appropriately placed facets can maximize the amount of light that reflects from refracts or tabletops and bounces off the internal walls to the eyes of an observer.

The observable impacts of the external and internal interactions with greying light are what establishes the brilliance of a diamond. Scintillation will be caused by an equal balance of light and dark spots creating a crisp of clear pattern with no distracting dark outline. Once the light exists the gem, fire is caused as the light is dispersed into the rainbow of shadowlike colors. In case the source of light, diamond or the viewer moves, the spots of light that spackle (flash) will be noticeable.


The girdle in the GIA cut grading system refers to the narrow unit that separates the pavilion from the crown and works as the stone’s setting edge. It plays a role in lessening the risk of damage when adequately thick. It comprises of 16 hill and 16 valley positions formed by the final cutting. The average thickness is calculated by an optical gadget and its percentage computed using the available formulae. So, the maximum and minimum verbal description depend on the decision of GIA lab graders. The thickness is evaluated as a range from the thinnest to the thickest valley spots. The maximum and minimum girdle thickness is measured via the use of the non-contact optical measuring gadget. You can also measure with the GIA multipurpose Gemological Reticule and a gemological microscope. Girdle thickness evaluation continues to depend on visual observations. This is because the measured outcome results are vulnerable to variability intrinsic in measurement gadgets acceptance and clarity features. This is true when differentiating between very thin and exceptionally thin girdles.

Diamond culet size:

A diamond culet is a tiny spot beneath the pavilion, where the pavilion and facet meet. In many stones, the pavilion facets are uniformly crafted at the right angle and close at the perfect point, making no culet. If the pavilion facet does not meet at an ideal point, the culet will be a rough or polished facet. The existence of the culet adds an extra facet to the stone’s cumulative number of facets.

Rating of culet size

A diamond culet can be rated from extremely large to none. When loose diamonds are sent for certification, the stone is observed face up to determine the size of the culet, and from sideways to define the angle of the culet. A sharply angled culet is not evaluated as a culet but an additional facet. For approved diamonds with culets in the range of small to extremely large, diamond culet size is expressed as a percentage relative to the diameter.

Here’s a description of culet size

None: since there is no space beneath the pavilion, light cannot space from the culet and is bounced back. This is a requirement for well-cut grade diamonds.

Very small : the culet comprises a tiny opening that can't be seen without magnification. Since light seepage is reduced, it cannot affect the gem’s light performance and spackle.

Small: this culet has a noticeable opening under magnification that leaks some light. However, the diamond will have great spackle and high brilliance.

Medium: a visible opening is noticeable under the magnification and tiny without it. This will affect the light performance of the stone since light leaks via the pavilion’s center.

Large: the culet is visibly open and serves as a facet. Leakage of light takes place, and it affects the brilliance of the stone.

Very large: a vast opening is available in the stone. You can’t see the stone’s brilliance cut.

Crown angle:

A crown serves as a window that drives light and defining the brightness of the stone. It also serves as a prism that disperses light giving the size, of the fire and the angel of the crown facet. This will help you define the amount of fire the diamond releases. The crown facet has another function which is to curvature light such that what you observe via the crown is a shifted version of what you can see via the table.

A crown angle refers to the angle created where the girdle plane meets the bezel facets. It’s the same as the crown height. So, a higher crown means a greater angle. The majority of diamonds have crown angels that range from 25 to 35 degrees. Diamonds whose crown angles are shallow than 25 degrees tend to be bright, but they are venerable to damage than gems with high crowns.

Diamonds with shallower crowns must be placed on mountings to secure the girdle spot such as bezel settings that surround the gem with a rim of precious metals. Shallow stones are ideal to be used in jewelry where they are not susceptible to damage. Diamonds cut from rough are a task for the craftsman who attempts to achieve the largest girdle diameter and high weight retention. For this reason, they are usually cut with shallow pavilions and crowns. Additionally, they have a large table percentage and thin girdles.

Ideal crown angels

The crown angle tries to compensate for the bending light by the initial pavilion. In this case, the general concept is that the crown angle must be shallow if the pavilion angle is steeper to compensate for light and vice versa. This implies that there is a crown angle which maximizes the right return for any designated pavilion angel.

Experts calculated that the perfect crown angle is 34.5 degrees paired with 40.75 degrees of pavilion angle. Bear in mind that for stone with a 40.7 pavilion angle that curves light too much, you require a crown angle of 35 degrees so that you can compensate. Similarly, if a stone with a pavilion angle of 41 degrees doesn’t bend light well, you will need a shallower crown angle of 43 degrees to compensate.

The pavilion angle:

The lower girdle facet and pavilion serve as mirrors, and its reflective index defines a stone's ability to work as a mirror. The reflective index defines the viewpoint that light is curved at while it gets into the diamond. The angle is vital since stone can only serve as a mirror when the light hit at a perfect angle that is greater than its acute angle.

A pavilion angle plays a vital role in determining whether a diamond is proportioned correctly, or if the stone will require re-cutting. When it comes to mounting, the Table reflection technique is useful in identifying the pavilion depth/angle. In most cases, there is a space in the mounting under the culet that allows a direct measurement of the entire depth.

You will know a pavilion is deep if the general depth is more than 63 percent with a shallow crown. For instance, visually, you identify a flat crown by looking at the side profile of the stone and a normal, medium girdle.

Ideal pavilion angles

40.75degreees is the ideal pavilion angle according to the mathematics professionals. Interestingly, artisans were cutting the stones with this angle before it was defined. Diamond cutters claim that beyond 41 degrees are too steep. Retailers selling badly cut stones will lure you by saying that a cliff of 41 degrees ridiculous. However, according to physics, there is a critical angle before light escapes. What takes place, in reality, is not a cliff, but a smooth transition from stronger to weaker light return as more rays escape.

The aspect you need to remember is that transition happens around 41 degrees. Therefore, unless you are observing a super-ideal gem cut at 40.9 degrees, then you are good to choose something close to 40.75 degrees. While using a light ray tracing, researchers have found that a pavilion angle that is shallow than 40.5 degrees is extremely shallow and will result in light leakage and obstruction.

Painting and Digging Out:

Printing and digging out refers to the faceting methods for the half facet that influences the three-dimensional settings of the stone. They include the relative position, horizontal angles and distance from the center of the stone. The painting and printing out methods are applied to save the stone’s weight during the cutting procedure. They get rid of attachments near the girdle or influences the face-up appearance of the gem. Bear in mind that the effect of painting and digging out methods on cut grading is affected by the virtual distinguishability of the techniques and if it is utilized by the pavilion only, crown only or both.

GIA Diamonds

More about Diamond Cuts:

Diamonds have to be cut to get a shape, the actual cut of a diamond refers instead to its proportions. The depth and width at which a diamond is cut determine its characteristics. The cut of the diamond regulates brilliance and radiance. Diamonds are typically cut in brilliant cuts and fancy cuts. Brilliant cuts are perhaps the most popular and are often the most saleable. Fancy cuts include modified brilliants, step cuts, mixed cuts and rose cuts. Diamonds with rose cuts are generally only seen in antique jewelry. Rose cushion cut jewelry is steadily making a comeback as an antique appeal is becoming more popular today.

The amount of light and the way it exits a diamond is dependent upon the type of cut and is often referred to as the quality of the cut. If the cut is too shallow compared to the width of the cut, for instance, the light will directly exit the diamond with little to no reflective qualities. Thus, the diamond will appear dull and lusterless. Likewise, if the cut of the diamond is too deep, the light will escape from the sides of the diamond rather than through the diamond. This cut will also appear dull. A Signature ideal cut is perhaps the rarest and highest quality cut available. With this cut, the light that enters the diamond is reflected in such a way that it encompasses the entire diamond and allows for maximum brilliance and radiance. The quality of a cut can be Signature ideal, ideal, very good, good, fair or poor.

Diamonds are cut from stones in a wide variety of shapes known as cuts. While most stones can be cut into any of these shapes, for best effect the natural shape and qualities of the diamond itself will determine which shape is chosen. If you are custom designing your diamond jewelry or if you are shopping for an already designed piece, it is always helpful to have an understanding of the terminology used to describe the different cuts used for diamonds. The name of the cut refers to the shape of the diamond when viewed from above.

The cut of the diamond is one of the most important aspects to attributing a value to a diamond and can sometimes account for up to one third or more of the diamonds appraisal. Most commonly the reason for this is because certain cuts waste more of the raw diamond in the cutting process. Thus, the diamonds that waste more cost more.

In addition to the shape, different cuts will affect in different ways how the light passes through the diamond. In this way, how a diamond is cut will also determine its brilliance and sparkle.


1. ROUND Cut Diamond: One of the most common shapes for a diamond used on rings, pendants, bracelets or earrings is the round shape. The sides of the diamond are faceted to allow the light to reflect across the centre of the diamond, creating the fire and sparkle that is the hallmark of beautiful stone. Round diamond cuts are very popular for solitaire style rings and are ideal for stud type earrings.

2. PRINCESS Cut Diamond: Another very common diamond cut for the large or centre stone or in a solitaire style setting is the princess cut. This cut is the square to rectangular cut that is seen in many of the antique as well as modern settings. Diamonds used for the princess cut have to be superior in clarity to prevent the color from showing at the points or corners of the cut.

3. Cushion Cut Diamonds: A unique diamond shape that is makes for a very interesting alternative to the princess or oval cut diamonds. It has rounded corners, and larger facets that help bring out its brilliance. The cushion diamond is a beautiful combination of round and square and makes quite a statement in a solitaire engagement ring setting.

4. EMERALD Cut Diamond: The emerald cut is a rounded rectangle with a pavilion or faceted side, typical of what you would see in a well-cut emerald gem. Like the princess cut, the emerald shape requires a very clear diamond of high quality to preserve the clarity of the stone.

5. ASSCHER Cut Diamond: A less common cut is the Asscher, which is a square version of the emerald cut. The difference between the Asscher cut diamonds from the emerald cut diamond is that the Asscher is square rather than rectangular. This cut is not a traditionally chosen cut for diamond engagement rings, however, its unique blocked corners make it a great choice in a setting that does not hide this feature.

6. MARQUIS Cut Diamond: The marquise cut is an elongated shape with both the top and bottom ending in a noticeable point. This shape is ideal for enhancing the size of the solitaire diamond as it draws the eye along the cut of the side, giving the appearance of a much larger carat diamond. The marquise cut is seen in both older and more modern settings and can be accentuated with baguette style diamonds or gems.

7. PEAR Cut Diamond: The pear shape is similar to the marquise but with one end rounded and one end pointed. This diamond cut can add slimming and elongating effect to the ring finger and is considered one of the classic diamond shapes. Pear-shaped diamonds are also popular in earrings and necklaces where they give the impression of length.

8. Radiant Cut Diamonds: With its square shape and trimmed corners, the radiant cut diamond is a very versatile diamond that combines the classic emerald shape with the brilliance nearly matching a round cut diamond. It is quite similar to the princess cut but is usually slightly more in the shape of a rectangle, and it has its corners blocked.

9. HEART Cut Diamond: Heart shaped diamonds are considered the ultimate and most romantic of all the diamond shapes. Not only because of its shape but also because of the skill required by the diamond cutter to bring out the natural brilliance of the diamond and create the smooth shape of a heart. With its tapered point and rounded lobes the heart diamond cut makes for an amazing looking engagement ring.

10. PILLOW Cut Diamond: The pillow cut is a combination of the round and princess cut with lots of facets resulting in sparkle and fire. The cushion cut is one of the most common cuts seen on antique diamonds and is very popular in pendants and other large settings.

11. Oval Cut Diamonds: As the name says, the oval cut diamond is oval and the most near to that of the round cut diamond. This particular cut features a flattering, longer outline that combines with the brilliance of a round cut diamond. Additionally, oval cut diamonds are popular engagement ring choices because their length can accent longer, slenderer fingers.


It should be noted that there is no distinct "best" diamond cut available. Take for example Tolkowsky's cut. While this diamond cut can have exclusive parts that make it distinctive from the rest, there are other diamonds that will have some similarities in characteristics as well. Only a few numbers of diamonds will have the perfect Tolkowsky cut and formation. The "perfect" Tolkowsky cut will only be visible on finely and expertly cut diamond stones.

But some diamond craftsmen are using their licenses in creating similar cut diamonds and selling them at cheaper rates. This kind of problem has been mixed with the fact that there isn't any final industry agreement on how diamonds can be called this and that type of cut. Another issue when buying diamonds based on cuts is that each one will be defined with some personal touch in mind. Famous cuts in different regions reflect these kinds of preferences.

  1. Check out the grade of how the diamond was cut. To do this, look at the diamond grade certificate to find even better stones cut at even better forms. Only stick with the "Excellent," "Very Good," and "AGS0" grades, according and trusting the grading company.
  2. After collecting your prospective diamonds, try to examine this short list by putting them under different light conditions. Grading laboratories and companies use fluorescent lights for grading their stones. This unfavorably affects the diamond's appearance. Hence, try viewing the diamond under several fluorescent light, incandescent light, and direct sunlight.
    Doing this will surely help in getting the feel of the personality the diamond gives off. Compare your very own short list to others so that you can distinguish the impact and effect each cut has on the stone's fire and brilliance elements.
  3. Always have the final say when diamond buying. Make your own decision based on what you truly desire. Opt for the diamond that makes you feel "right" and comfortable. Or the one that grabs your attention when you try to move it here and there in.

Generally, the more depth a diamond has, the more brilliance it has. To calculate a diamond's depth percentage, divide depth by width and multiply by 100. Before a diamond is cut, the diamond cutter has to analyse the diamond. Two factors are important. These are maximizing the return on the investment and how fast the diamond can be sold. To maximize the return on a diamond, the cut is important. The cutter has to look at several factors. These factors are weight retention, color retention, the shape of the rough stone, and the location of inclusions and flaws.

Diamond cutting involves four different methods. These methods are cleaving, sawing, bruiting/cutting, and polishing. Cleaving is the first step in diamond cutting. It cuts a rough diamond down to a manageable size using a wax or cement mold, the cutter cleaves the diamond along it's the weakest point called the tetrahedral plane. At other times, a diamond cannot be cleaved when there is no point weakness, and the cutter uses either a phosphor-bronze saw blade or a laser. However, lasers take a long time.

After the diamond is a reasonable size, the cutter uses either bruising or cutting to give them their shape. When diamonds are cut by hand, it is called bruiting while cutting uses a lathe. In either process, one diamond is used to cut another. After the diamonds is cut, the cutter uses a rotating polishing wheel coated with an abrasive powder to finish the diamond. When a diamond is cut, 50% of the stone can be lost. Considering so many qualities of a diamond are dependent upon cut, the cutter's skill is very important.


The cut of the diamond stone should not be your only basis when buying diamond. There are other important factors to consider such as how the price will fit your budget. Before deciding on what kind of diamond cut to go with, consulting with reputable experts in diamond cutting and polishing should be checked with.