The Diamond Cut Definition: Understanding the Anatomy of a Sparkling Gemstone

  • Billy Cobb
  • Jun 16, 2023
The Diamond Cut Definition: Understanding the Anatomy of a Sparkling Gemstone

The Importance of Diamond Cut

When it comes to diamonds, cut is considered the most crucial of the 4 Cs (cut, color, clarity, and carat weight). Diamond cut determines how well the stone reflects light, which in turn affects its brilliance, fire, and scintillation, all essential components of the diamond’s overall beauty.

Properly cut diamonds can maximize the amount of light that enters the stone, reflects it back to the viewer, and creates the illusion of a bigger, brighter diamond. On the other hand, if a diamond is cut too shallow or too deep, light leaks out through the bottom or sides of the diamond, resulting in a lack of sparkle and poor overall visual appeal.

For example, a well-cut diamond will have a symmetrical arrangement of facets that create a pattern of light and dark areas, while a poorly cut diamond will have asymmetrical or misaligned facets that create dark spots or dull areas.

Another important aspect of diamond cut is finish, which refers to how well the diamond cutter has polished the diamond’s surface. A high-quality finish will produce a mirror-like sheen that enhances the diamond’s beauty, while a poor finish can create scratches or nicks that detract from its value.

It’s also worth noting that a diamond’s cut grade (excellent, very good, good, fair, or poor) can affect its price, with higher cut grades generally commanding higher prices. This is because a well-cut diamond is rarer and more desirable than a poorly cut one.

In summary, the importance of diamond cut lies in its ability to bring out the diamond’s natural beauty, maximize its sparkle and fire, and ultimately enhance its overall value.

Why Diamond Cut Matters

Diamonds are a highly sought-after gemstone, and their value is determined by several factors including their color, carat weight, clarity, and cut. The cut of a diamond is one of the most important factors in determining its overall quality. A well-cut diamond will have better light performance, sparkle and brilliance. Cut refers to the angles, proportions, symmetry, and other factors that determine how well the diamond reflects light.

When a diamond is cut properly, light enters through the top of the diamond (known as the table) and is reflected internally from one facet to another before finally being reflected back out through the table. This is what creates the sparkle and brilliance that makes diamonds so desirable. If a diamond is cut too shallow or too deep, the light is not properly reflected, and the diamond will appear dull and lifeless.

Diamond cut is often confused with the shape of a diamond (such as round, princess, or emerald), but these are two completely different things. The shape refers to the outward appearance of the diamond, while the cut refers to the angles and proportions of the facets within the diamond. A diamond can be cut in any shape, but its value will always be determined by how well it has been cut.

There are several different factors that go into determining the quality of a diamond’s cut, including:

1. Proportions

The proportions of a diamond refer to how the different facets are arranged and how they relate to one another. The most important proportion is the depth of the diamond (measured from the table to the culet), as this determines how well the light will be reflected. If the diamond is too deep or too shallow, it will not reflect light properly.

2. Symmetry

Symmetry refers to how evenly spaced and aligned the facet arrangements are in the diamond. A diamond with good symmetry will have each facet reflect light in the same way, resulting in an even pattern of sparkle and brilliance. If the symmetry is poor, the diamond will appear lopsided and will not reflect light evenly.

It’s important to note that the symmetry of a diamond is not the same as its shape. A diamond can be any shape, but the symmetry refers to the evenness of the facets within that shape.

3. Polish

Polish refers to the smoothness of the diamond’s surface and the quality of the facets. If a diamond has poor polish, it will have scratches or other imperfections on its surface, which can affect how well it reflects light. A diamond with good polish will have a smooth surface and well-defined facets that reflect light evenly.

Overall, the cut of a diamond is one of the most important factors in determining its value and beauty. A well-cut diamond will have better light performance, a higher level of sparkle and brilliance, and will be more valuable than a poorly cut diamond. When choosing a diamond, it’s important to consider all of these factors in order to ensure that you get a diamond that is both beautiful and valuable.

Famous Diamond Cuts

Diamonds attract admiration and fascination from people across the globe. They are the most preferred precious stones for jewelry and investment. But what defines the beauty and brilliance of diamonds? It’s the way the diamond is cut that determines its visual appeal. A diamond cut refers to the shape, proportions, and finish of a diamond. Today, we will discuss the most famous diamond cuts that are popular among buyers and collectors.

Round Brilliant Cut

The classic Round Brilliant Cut is the most popular diamond shape worldwide, commanding about 75% of all diamond sales. It is a round-shaped diamond with a faceted surface. The bright, dazzling look of a Round Brilliant Cut diamond is the result of its 58 precisely cut facets that allow maximum reflection and refraction of light. This cut is ideal for engagement rings and other jewelry pieces as it offers timeless beauty and elegance.

Princess Cut

The Princess Cut is the second most famous diamond cut after the Round Brilliant Cut. It is a square or rectangular-pyramid-shaped cut with pointed corners, often preferred for engagement rings. The Princess Cut gives the illusion of a larger diamond, thanks to its faceted surfaces that reflect light in intricate patterns, giving it a stunning sparkle. The cut was first developed in 1980 and has since become a fashionable option for engagement rings.

Cushion Cut

A Cushion Cut diamond is a timeless classic that has been around since the 18th century. It is a square or rectangular cut with rounded corners, resembling a pillow or cushion. This cut has larger facets with a higher crown that gives it a brilliant sparkle and a vintage look. Cushion Cut diamonds are often used in wedding and engagement rings.

Oval Cut

The Oval Cut diamond is a modified version of the Round Brilliant Cut with a similar faceted surface. It has an elongated shape that gives the appearance of a larger diamond. The Oval Cut can be set east-west or north-south, depending on the stone’s proportions and setting. The cut has a high brilliance and fire, making it a popular choice for engagement rings, necklaces, and earrings.

Emerald Cut

The Emerald Cut is a rectangular-shaped diamond with cropped corners that create a stepped facet pattern. Unlike other cuts, the Emerald Cut has fewer facets, but they are larger and arranged in parallel lines, producing a hall-of-mirrors effect. The cut emphasizes clarity over brilliance, giving the diamond a more understated elegance. The cut is often used for engagement rings and is a timeless classic, dating back to the Art Deco era in the 1920s.

In conclusion, when it comes to buying diamond jewelry, the cut is one of the most critical factors to consider in determining its value and beauty. Each cut has its unique appeal, ranging from timeless elegance to modern brilliance. Ultimately, the choice of the cut depends on the buyer’s style, preference, and budget.

Cut Grades

Diamonds are one of the most sought-after precious stones, known for their exquisite beauty and eternal sparkle. However, not all diamonds are created equal, and one of the most significant factors that determine their value is the cut grade. Diamond cut refers to the number, size, and angle of the facets, as well as how well they interact with light.

Diamonds are given cut grades of Excellent, Very Good, Good, Fair, and Poor based on their light performance. The cut grade is determined by evaluating the proportions, symmetry, and polish of the diamond.

Excellent Cut

An Excellent or Ideal cut diamond is the highest grade given to a diamond. This grade is reserved for those diamonds that have been cut with optimal proportions and symmetry, allowing maximum light performance. An excellent cut diamond will produce maximum brilliance, fire, and scintillation.

The proportions of an Excellent cut diamond are such that light is reflected from one facet to another before reflecting back out of the diamond’s top. This results in the most brilliance and fire possible from the diamond. An ideal cut diamond is also perfectly symmetrical, with each facet reflecting light uniformly.

Very Good Cut

The second-highest cut grade is Very Good. This grade means that the diamond has very good proportions and symmetry, resulting in excellent light performance. A very good cut diamond will exhibit almost as much brilliance and fire as an excellent cut diamond, but at a slightly lower price point.

Very Good cut diamonds have proportions that allow for a high level of light return, but they may have slight variations in symmetry or polish that can affect their overall light performance. However, these minor variations are usually not noticeable to the naked eye and can be an excellent choice for those seeking high-quality diamonds at a more affordable price.

Good Cut

A Good cut diamond is the entry-level grade for a diamond with good light performance. Good cut diamonds have proportions that allow for some light return, but they do not exhibit the same depth of brilliance and fire as higher cut grades.

Good cut diamonds may also have slight variations in symmetry or polish that can affect their overall light performance. However, these diamonds can still be an excellent option for those working with a tighter budget or looking for a slightly larger diamond.

Fair and Poor Cut

The Fair and Poor cut grade is reserved for diamonds that do not meet the minimum criteria for light performance. These diamonds may have poorly proportioned facets, lack symmetry, or have an uneven polish. As a result, they exhibit very little brilliance, fire, or scintillation, making them less valuable than higher cut grades.

While Fair and Poor cut diamonds may seem like a more affordable option, it is recommended to invest in a higher cut grade to ensure the best possible light performance and overall quality of the diamond.

Overall, the cut grade of a diamond is an essential factor to consider when investing in a diamond. An Excellent cut diamond will exhibit the most exceptional brilliance, fire, and scintillation, making it a valuable investment. However, lower cut grades can still provide an excellent option for those on a budget, as long as they still meet the minimum criteria for light performance.

Certification of Cut

When it comes to purchasing a diamond, the cut plays a significant role in determining the stone’s beauty and brilliance. A well-cut diamond reflects light in a way that maximizes its fire and sparkle, making it the most popular choice for engagement rings and other special occasions. Due to this reason, several organizations have established standards that certify diamond cut quality.

The two most reputable diamond grading organizations that provide certification for diamond cuts are the Gemological Institute of America (GIA) and the American Gem Society Laboratories (AGSL). Both groups have established a grading system that assesses a diamond’s cut quality, including its proportions, symmetry, and finish.

The GIA created the first diamond cut grading system in the 1950s, called the GIA Cut Grading System. The system measures a diamond’s cut based on its brightness, fire, scintillation, and how well it reflects light. The GIA cut grading system consists of five grades, starting with Excellent and finishing with Poor. With the GIA certification, consumers can be confident in the diamond’s cut quality and that it will provide maximum sparkle and brilliance.

The AGSL system is newer, created in the early 2000s. The organization has similar criteria to the GIA, but it includes additional metrics focused on a diamond’s light performance. The AGSL certification system is more rigorous, with eleven different cut grades ranging from Ideal to Poor.

Both certification systems are used to determine the cut quality of a diamond, with different terminology. For example, the AGSL’s Ideal stands for the GIA’s Excellent. When shopping for a diamond, being aware of these two systems is essential as they reassure customers of the diamond’s cut quality standards.

It’s important to note that while the GIA and AGSL’s cut grading systems are much the same, they don’t certify diamonds for color, clarity, and carat weight. These four qualities are each crucial when purchasing a diamond, and all factors must be weighed up together for an unclouded understanding of its value and quality.

The certification process for the cut only begins with a diamond’s proportions. Measurements are taken of the diamond’s table, girdle, depth, and width, and then a mathematical equation uses the ratio of the size to determine the cut grade. From there, the grader considers other elements such as symmetry, polish, and potential light leakage.

Many diamond retailers will state that their diamonds are certified by internal certification systems, commonly referred to as “in-house” certifications. These often include branded names or logos, but unfortunately, these are usually less reliable and less stringent in grading. While these distinctive brands may give the impression of a superior product, the AGSL and GIA remain the benchmark organizations when it comes to professional diamond certification.

In conclusion, when buying a diamond, it’s essential to acquire certification for its cut quality. You can be assured of the cut quality and value of your diamond by obtaining certification from the AGSL or GIA organizations. These qualifications offer the highest level of confidence that the diamond’s brilliance and sparkle are undeniable, providing an exceptional piece to last a lifetime.

Factors Influencing Cut Quality

Diamond cut quality is one of the essential factors influencing the gemstone’s overall beauty and value. A diamond’s cut is determined by several factors, some of which can be measured objectively and others which are more subjective. Four primary factors impact diamond cut quality that experts rely on to evaluate a diamond’s worth. These factors include Depth Percentage, Table Percentage, Girdle thickness, and Symmetry.

Depth Percentage

Depth percentage is the measure of the height of a diamond divided by its diameter. It is one of the most critical factors in determining a diamond’s overall cut quality. A shallow depth percentage causes light to escape from the sides of the diamond, resulting in less sparkle and brilliance. On the other hand, a deep depth percentage causes light to escape from the bottom, making the gemstone appear dull and lifeless.

Table Percentage

This factor measures the size of the diamond’s table or its flat top versus the diameter. The table is where most of the light enters the diamond and reflects back to the viewer’s eye. A well-cut diamond should have an ideal table percentage that provides maximum light reflection and sparkle. Too small or too large of a table can cause a diamond to appear dull, reducing its beauty and value.

Girdle Thickness

Girdle thickness is the distance between the diamond’s crown (top) and its pavilion (bottom). This factor affects the diamond’s durability as well as its cut quality. If a diamond has a thin girdle, it may be prone to chipping or breaking. Conversely, a diamond with a thick girdle may not reflect as much light and can appear bulky in appearance.


A diamond’s symmetry measures the precision and balance of its cut. A well-cut diamond appears perfectly symmetrical and displays beautiful patterns of reflecting light. If a diamond has imperfections in its symmetry, it can affect its overall beauty and value.

Overall, achieving high cut quality is a delicate balance between all these different factors. Diamond cutters consider many variables when cutting a diamond to ensure the gemstone is as beautiful and valuable as possible. Understanding these factors will help buyers make informed decisions when purchasing diamonds and ensure they get the best value for their investment.

Cut and Diamond Value

Diamond cut refers to the way a diamond has been cut and shaped to ensure the maximum amount of light enters it and reflects back out. Cut is considered one of the most important factors in determining the value of a diamond. A well-cut diamond can make all the difference in terms of how the diamond looks, sparkles, and refracts light.

Diamond cut affects the overall appearance of the diamond and how it ultimately performs in terms of fire and brilliance. A good diamond cut is one that is proportionate, symmetrical, and with good light performance. A well-cut diamond will yield the maximum amount of brilliance and dispersion, emitting white and colorful flashes when viewed from different angles. That’s why diamonds with well-cut or excellent cutting grades are more valuable and desirable than poorly cut ones, which are less shiny and less appealing to the eye.

There are currently 5 cut grades used by the GIA and AGS: Excellent, Very Good, Good, Fair, and Poor. Excellent cut means that the diamond has the best reflection, fire, and dispersion. It is proportioned and symmetrical that its light interaction produces the highest sparkle. A very good cut is slightly lower in quality, but still with great fire, good light performance, and a clean appearance.

Next comes the good cut, which reflects most of the light but is not as brilliant as the first two grades. A fair cut is below this in quality, with reduced brightness and sparkle, while poor cut grades are barely acceptable, with much of the light escaping through the sides and bottom of the diamond, giving it a lusterless appearance.

Additionally, diamond cutting includes the following 7 aspects:

7 Aspects of Diamond Cut Definition


The table is the flat surface on the top of the diamond. It is the largest facet of the diamond and directly affects how much light enters and reflects within the diamond. A properly executed table enhances the diamond’s overall brilliance and luster.

Depth Percentage

The depth percentage measures the distance from the bottom of the diamond (pavilion) and the table’s top (the largest facet of the diamond). A shallow diamond cut allows more light to escape from the sides; a deep cut may cause loss of light through the bottom of the diamond.


The crown is the upper part of the diamond between the girdle and the table. It is responsible for the diamond’s first impression and ideally should be polished to be perfectly symmetrical to allow light to reflect from one facet to the other, resulting in an impressive display of brilliance.


The girdle is the outer edge of the diamond ring. A well-polished girdle can add beauty, durability, and value to the diamond. A thick diamond girdle, however, will add weight to the diamond and affect its overall proportions.


The culet of the diamond is the very bottom point. A culet protects the point and focuses light when it exits the stone. A large or visible culet can make the diamond appear less valuable.


The pavilion is the lower part of the diamond from the girdle to the culet. It’s responsible for the diamond’s fire and brilliance by reflecting light back up to the table through its facets. Pavilions that are too deep or too shallow can reduce the overall performance and beauty of the diamond.


The symmetry refers to how the facets align in opposition to each other. Misaligned facets can cause dark areas or distraction in the diamond’s appearance. Excellent symmetry allows for ideal light reflection and refraction and permits the diamond to shine brightly under any light source.

A diamond with a high-quality cut has the maximum potential of the diamond to sparkle and shine. It’s important to choose a diamond with a good cut to maximize your investment and enjoy it for years to come.

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