Diamond Education

Diamond Cut

In the fascinating world of diamonds, the quality of a gemstone is often defined by the "Four Cs" - Cut, Color, Clarity, and Carat. Each plays a crucial role in determining the diamond's beauty and value, with 'Cut' arguably being the most critical. This element of the Four Cs is solely influenced by the skill and precision of the diamond cutter, as it relates to the proportioning, alignment, and finish of a diamond's polished facets or faces. It's important to understand the difference between a diamond's 'cut' and its 'shape'. While 'shape' refers to the overall geometric form of the diamond such as round brilliant, marquise, or princess, 'cut' specifically addresses the facet arrangement and the craftsmanship used to shape the diamond.

Understanding the cut of a diamond might seem daunting due to its technical nature. However, having a basic comprehension of this aspect is crucial for anyone looking to make an informed diamond purchase. This article aims to provide an in-depth understanding of the diamond cut - how it affects a diamond's aesthetic appeal and market value, the science behind analyzing a diamond's cut, the concept of 'Ideal' cut diamonds, and practical advice to consider when choosing a high-performing diamond.


The Importance of Cut

The cut of a diamond commands paramount significance due to its direct influence on the gem's brilliance, fire, and scintillation - the trio that lends the diamond its breathtaking beauty. A meticulously cut diamond unleashes its full potential, magnifying its brilliance (the total light reflected from a diamond), fire (the dispersion of light into the colors of the spectrum), and scintillation (the sparkle seen when the diamond moves).

When a diamond is cut with perfect symmetry and proportions, the light entering it is refracted and reflected optimally, resulting in a high percentage of light being returned to the observer's eye. On the contrary, a poorly cut diamond allows light to leak out from the bottom and sides, leading to a significant reduction in its sparkle and brilliance.

Looking for the best cut quality diamonds? Try the A CUT ABOVE diamonds from Whiteflash as my top recommendation, I would also consider the Astor by Blue Nile and True Hearts by James Allen.

To ensure that a diamond's cut enhances its light performance, a diamond cutter must show dedication to precision, sometimes even compromising on the rough diamond's carat weight to obtain an excellent cut. This precision requires an investment of time and can lead to higher production costs, thus increasing the value of well-cut diamonds. However, the resultant sparkle, brilliance, and fire make the investment worthwhile, rendering these diamonds visually more appealing and, consequently, more valuable in the market.

In this age of technology, assessing the light performance of a diamond has become easier than ever before, with the availability of light-performance images and high-definition videos. These visual tools provide a detailed representation of how well a diamond interacts with light, offering a comprehensive understanding of its cut quality. They serve as invaluable aids for both experts evaluating diamond cut quality and consumers seeking to make an informed diamond purchase. As you continue your journey into the world of diamond cuts, remember that the allure of a diamond often rests more on the quality of its cut than anything else.

In the universe of well-cut diamonds, a specific type of precision cut known as Hearts and Arrows (H&A) stands out. The moniker 'Hearts and Arrows' is derived from the unique visual pattern observed under a special reflector device when inspecting these diamonds. An H&A diamond exhibits eight symmetrical arrows when viewed from the top (crown) and eight perfectly formed hearts when seen from the bottom (pavilion). This intricate pattern is a testament to the exceptional optical symmetry of the diamond, a result of the diamond cutter's meticulous craftsmanship and attention to detail.

But the appeal of Hearts and Arrows diamonds extends beyond the pleasing symmetrical patterns. When all facets are precisely aligned in three dimensions, the diamond is tuned for optimal performance, enhancing its brilliance, fire, and scintillation. It's important to understand, however, that an excellent H&A patterning doesn't necessarily guarantee ideal light performance. Thus, when selecting a Hearts and Arrows diamond, make sure to evaluate its cut quality comprehensively, considering other critical aspects like proportions, facet alignment, and polish.

The Art of Diamond Cutting

Diamond cutting is an intricate blend of art and science, requiring a deep understanding of the diamond's physical properties, a keen eye for detail, and an immense level of precision. From the moment the diamond is sourced from the mine, the journey of a diamond cutter begins with envisioning the final masterpiece within the rough stone. The goal is to maximize the diamond's potential beauty without wasting the precious raw material, which involves making critical decisions on the diamond's eventual shape, size, and cut quality.

The diamond cutter must make precise calculations and assessments to determine the best way to cut the diamond to yield the maximum carat weight while still preserving its inherent beauty. This balance between size and beauty largely determines the final value of the diamond. To achieve this, the cutter must take into consideration the natural crystal structure of the diamond, internal flaws or inclusions, and the desired final shape.


Once the decisions are made, the actual process of cutting the diamond involves several stages including marking, cleaving or sawing, bruting, and polishing. Each step is carried out with an exacting level of accuracy to ensure that the facets are perfectly aligned and proportional, and that the finish is pristine.

Today, the art of diamond cutting also integrates advanced technology. Tools such as laser cutting machines, computer-aided design (CAD) systems, and optical analysis devices allow for a level of precision and consistency that was unthinkable in the past. Despite these advancements, the role of the diamond cutter remains essential. The cutter's expertise and skill in interpreting and responding to the unique features of each diamond are what bring out the diamond's best light performance and maximum beauty.

Who sells the best cut diamonds? Try the A CUT ABOVE diamonds from Whiteflash these are the best quality cut diamonds that come with light performance images, I would also consider the Astor by Blue Nile and True Hearts by James Allen.

In the context of Hearts and Arrows diamonds, the diamond cutter's task is even more demanding. Creating this pattern requires extremely precise cutting techniques that maintain exceptional optical symmetry. This high level of craftsmanship can be seen as the pinnacle of the diamond cutter's art.

Understanding Diamond Cut Grades

The Gemological Institute of America (GIA) and the International Gemological Institute (IGI) are two highly respected gemological organizations that have developed their own diamond cut grading systems. These systems aid in the evaluation and comparison of diamonds, thereby helping buyers make informed choices.

GIA Cut Scale

The GIA's cut grading system for round brilliant diamonds ranges from Excellent to Poor. This system evaluates the cut quality based on factors like brightness, fire, and scintillation, weight ratio, durability, polish, and symmetry. With the recent acquisition of the American Gem Society Laboratories (AGSL), GIA has introduced an addendum AGS Ideal report for diamonds that meet the AGS's rigorous light performance standards. This means that diamonds can now be recognized as both GIA Excellent cut and also attain the higher AGS Ideal standard.

The AGS Ideal report is available as a digital supplement to the GIA diamond reports. It will be accessible starting in January 2023, for both natural and lab-grown round brilliant and fancy shape diamonds. The AGS Ideal report will cost an additional US$25. This report will segment the existing GIA Excellent grade further, distinguishing those diamonds that meet the highest standards of cut quality.

Looking for certified diamonds? Try WhiteflashBlue Nile, and James Allen.

The Ideal report is likely to showcase the AGS light performance grade of Ideal, including individual aspects of light performance like brightness, contrast, leakage, and fire, all designated as "0". In the AGS system, "0" equals Ideal, indicating zero net deductions in each light performance metric. The report will also feature an Angular Spectrum Evaluation Tool (ASET) light map, generated from a 3D scan of the diamond. This scan is used to perform computer ray tracing and determine the light performance cut grade.

On the other hand, the IGI evaluates cut in terms of Excellent, Very Good, Good, Fair, and Poor. The IGI’s cut grade evaluation considers factors such as proportions, symmetry, and polish.

Ultimately, a diamond's cut grade plays a vital role in determining its beauty and value. Therefore, when shopping for a diamond, it's important to closely examine the cut grade. However, this should not be the sole determinant. Viewing the diamond under various light conditions, analyzing light performance images, and observing HD videos can offer invaluable insights into a diamond's true light performance and overall beauty. For Hearts and Arrows diamonds, the patterning can be further verified through dedicated viewing tools to ensure the diamond's craftsmanship and quality.

The Anatomy of a Diamond

Understanding the anatomy of a diamond is essential for comprehending how a diamond's cut affects its brilliance and beauty. A diamond is composed of several parts, each contributing to the overall aesthetic and performance of the stone.

GIA Anatomy of a diamond

Table: The table is the largest facet of a diamond, located on the top. The size and angle of the table have a significant impact on the light reflection and dispersion within the diamond.

Crown: The crown refers to the upper portion of the diamond, extending from the table down to the girdle. The crown's facets refract light into different colors and angles, enhancing the diamond's fire.

Girdle: The girdle is the widest part of the diamond and separates the crown from the pavilion. It can range from extremely thin to extremely thick, and its thickness can affect the diamond's durability.

Pavilion: The pavilion is the lower part of the diamond, extending from the girdle down to the culet. The pavilion's facets are designed to reflect light back through the crown and table to the viewer's eye, contributing to the diamond's brilliance.

Culet: The culet is the tiny facet at the bottom of the pavilion. It's often pointed or very small, but when it's larger, it can appear as a dark circle when viewed from the top.

Depth: The depth refers to the height of the diamond, from the culet to the table. The depth percentage, which is the depth divided by the width of the diamond, is crucial to the stone's light performance.

Diameter: The diameter is the width of the diamond measured from edge to edge through the girdle.

These parts, each with their unique role, come together to form the diamond's cut, which has a profound impact on how the diamond interacts with light. The quality of the cut directly influences the diamond's fire (the dispersion of light into the colors of the spectrum), brilliance (the total light reflected from a diamond), and scintillation (the play of light you see with movement, also known as sparkle). Therefore, a proper understanding of a diamond's anatomy is integral to appreciating the craftsmanship involved in transforming a rough stone into a beautiful diamond.

Light Performance, Proportions, and Finish

The cut of a diamond determines how well it transforms light into the breathtaking sparkle that is characteristic of diamonds. This transformation process involves three primary factors: light performance, proportions, and finish, each of which plays a significant role in the overall appearance of a diamond.

  • Light Performance: This term refers to how a diamond interacts with light, taking into account aspects such as brightness (the amount of white light reflected from the surface and interior), fire (the dispersion of light into spectral colors), and scintillation (the amount of sparkle a diamond produces, as well as the pattern of light and dark areas). The light performance is largely determined by the diamond's cut, and diamonds with superior light performance are more appealing and valuable.
  • Proportions: The proportions of a diamond refer to the relationships between the different dimensions of a diamond (like the table size, crown angle, and pavilion depth) as well as the diamond's overall shape and symmetry. Proportions greatly impact how light travels within the diamond. If the proportions are ideal, light entering the diamond will be optimally reflected and refracted, leading to maximum brilliance and fire.
  • Finish: This term refers to the quality of a diamond's surface condition, as well as the precision and quality of the cut of each facet. The finish includes aspects such as polish (the smoothness of each facet) and symmetry (the exactness of the shape and arrangement of facets). A diamond with an excellent finish will have no noticeable scratches, nicks, or other flaws when viewed under magnification, and its facets will meet cleanly without any overlaps or misalignments.

It's important to note that these factors are not isolated; they interact and influence each other. For instance, a diamond with excellent proportions but poor finish may not perform well in terms of light performance. Similarly, a diamond with perfect light performance but poor proportions could lack the desired brilliance or fire. Therefore, a truly stunning diamond is the result of a meticulous balance of light performance, proportions, and finish.

Looking for the best cut quality diamonds? Try the A CUT ABOVE diamonds from Whiteflash as my top recommendation, I would also consider the Astor by Blue Nile and True Hearts by James Allen.

To ensure the consistency and reliability of these evaluations, make sure to ask for hearts & arrows images, ASET Maps, Sarine Reports, Ideal Scops as well as diamond images and HD Video.

Fire, Brilliance, and Scintillation

The true beauty of a diamond is revealed in its interaction with light, which is manifest in three primary visual effects: fire, brilliance, and scintillation. The fine balance and interplay of these factors create a captivating spectacle that makes diamonds an enduring symbol of beauty and prestige.

  • Fire: Also referred to as dispersion, fire is the ability of a diamond to break light down into its spectral colors, resulting in flashes of rainbow-like hues. The cut of a diamond plays a crucial role in this aspect; when the angles are correct, the diamond bends and disperses the light into its constituent colors, creating a mesmerizing effect. Fire is best observed in dim lighting or sunlight.
  • Brilliance: Brilliance refers to the quantity and intensity of white light returned from a diamond to the eye of the observer. It's a measure of the diamond's internal and external reflections of white light and is predominantly influenced by the diamond's cut and proportions. The better the cut, the more effectively the diamond can capture light and reflect it back, resulting in greater brilliance.
  • Scintillation: Scintillation encompasses two aspects — the amount of sparkle a diamond produces, and the pattern of light and dark areas that result from reflections within the diamond as it moves. It gives the diamond its lively play-of-light and dynamic character. In a well-cut diamond, every move creates a captivating flash of light, contributing to its overall scintillation.

The interplay of fire, brilliance, and scintillation creates the unique sparkle that characterizes a beautifully cut diamond. The ideal cut diamond optimizes these three effects, delivering an exceptional performance that enhances the diamond's inherent beauty.

It's important to remember that these visual effects are not only determined by the cut quality, but are also influenced by the diamond's size, shape, color, and even the lighting environment. Thus, personal preference plays a significant role in choosing the diamond that appears most beautiful to the individual observer. Professional grading reports from reputable organizations like the GIA and IGI, including their AGS Ideal Report, provide valuable guidance, but the ultimate choice should resonate with personal aesthetic sensibilities.

Ideal Cut Diamonds and the Labs

Understanding the intricacies of diamond cut quality can be complex, but fortunately, well-respected gemological laboratories like the Gemological Institute of America (GIA) and International Gemological Institute (IGI) have taken steps to provide consumers with comprehensive and comprehensible information. Their grading reports, particularly the new AGS Ideal Report offered by GIA, provide insight into the quality of a diamond's cut.

The term "Ideal Cut" was originally coined to describe round brilliant diamonds cut to precise mathematical proportions and angles, resulting in maximum light performance. Today, this term is also applied to other shapes that demonstrate superior cut quality. These diamonds are appreciated for their exceptional fire, brilliance, and scintillation.

GIA: GIA's diamond grading system is highly regarded for its rigorous standards and consistency. In their system, the top grade for cut in round brilliant diamonds is 'Excellent'. With the recent acquisition of AGS Laboratories, GIA now offers the AGS Ideal Report as an addendum to the traditional GIA report for eligible diamonds. This new feature recognizes diamonds that not only achieve GIA's 'Excellent' cut grade, but also attain the more stringent AGS Ideal cut grade. Furthermore, this report extends to fancy shape diamonds that meet these standards, a first in GIA’s history.

IGI: The IGI also employs stringent grading standards, offering detailed reports that provide consumers with the necessary information to make an informed purchase. IGI's grading system is trusted by diamond dealers and retailers worldwide.

Looking for certified diamonds? Try WhiteflashBlue Nile, and James Allen.

An Ideal Cut grading denotes that a diamond has been cut to the exacting proportions that maximize its ability to interact with light, creating optimal fire, brilliance, and scintillation. An 'Ideal Cut' grading from reputable labs like GIA and IGI ensures a diamond of exceptional light performance and beauty.

In the end, while understanding the cut grades and standards established by these labs is essential, personal aesthetic preferences and the overall balance of the diamond's 4Cs (Cut, Clarity, Color, and Carat) should also guide the diamond selection process. It is advisable to view light performance images and HD videos, and consult with a trusted diamond expert, to fully appreciate a diamond's beauty before making a purchase.

Diamond Analytics

Diamond analytics refers to the use of various techniques and tools for evaluating and understanding the quality and characteristics of a diamond. Given the importance of cut in a diamond's overall appearance and value, these analytics are key to assessing a diamond's light performance and other critical attributes.

Diamond analytics often employ advanced technology and methodologies to generate comprehensive data about a diamond. This data can be used by both professionals and consumers to gain insight into a diamond's cut precision, symmetry, light performance, and more.

  • Light Performance Images: These are images produced by specialized equipment that reveal how a diamond interacts with light. Devices like the ASET (Angular Spectrum Evaluation Tool) and Ideal-Scope produce color-coded images that show how much light a diamond is returning to the viewer's eye (brightness), how much light is leaking out of the bottom or side of the diamond (light leakage), and the diamond's contrast pattern.
  • HD Video: High-definition videos allow viewers to see a diamond from multiple angles and under different lighting conditions. This provides a more realistic view of the diamond's light performance and overall appearance, including its fire, brilliance, and scintillation.
  • AGS Ideal Report: As part of the diamond grading process, labs like the GIA now offer the AGS Ideal Report, which features an ASET light map. This is a graphic representation of a diamond's light performance, providing clear, objective data about its light behavior. This addendum report can be a powerful tool in diamond analytics.
  • Hearts and Arrows Viewer: This is a special tool used to assess the symmetry of a diamond's cut. When used on a round brilliant diamond with superior symmetry, the viewer displays a pattern of eight hearts when viewed from the bottom and eight arrows when viewed from the top. These "hearts and arrows" diamonds represent some of the most precisely cut diamonds in the world.

Who provides light performance images?

  James Allen Blue Nile Brilliant Earth Whiteflash
Hearts & Arrows


On request

Sarine Report

Ideal Scope

On request

HD Video

Please note: all Astor diamonds from Blue Nile come with GCAL or GemEx Diamond Light Performance certificate which will give you the ability to truly audit the light performance. In addition, Hearts & Arrows and ASET Maps are available on some True Hearts diamonds from James Allen.

In summary, diamond analytics help to provide a more complete and accurate picture of a diamond's cut quality and overall beauty. By leveraging these tools and technologies, consumers can make more informed decisions when purchasing diamonds.

Fancy Shape Diamonds

While round brilliant diamonds are the most popular choice for many, fancy shape diamonds provide a unique and diverse selection that allows individuals to express their personal style. Unlike round diamonds, fancy shape diamonds come in a variety of shapes, including princess, oval, pear, cushion, radiant, emerald, asscher, marquise, heart, and more.


Image Courtesy: James Allen

These diamonds are termed 'fancy' because they deviate from the conventional round shape.

Each of these shapes possesses its unique characteristics and charm:

  • Princess Cut: Characterized by its square or slightly rectangular shape, the princess cut has pointed corners and a brilliant style faceting arrangement for enhanced sparkle.
  • Oval Cut: Offering a modern twist to the round brilliant, the oval cut diamond elongates the finger and exhibits similar brilliance.
  • Pear Cut: This unique shape, also known as the teardrop, is rounded on one end with a tapering point on the other, creating an elegant and distinctive look.
  • Cushion Cut: This antique-style cut has a square or rectangular shape with rounded corners, resembling a pillow or cushion.
  • Emerald Cut: Known for its elegance, the emerald cut features a rectangular shape with cut corners. It is a step cut, which means it has parallel facets that create a hall-of-mirrors effect.
  • Asscher Cut: Similar to the emerald cut, but square, the Asscher cut has a unique X pattern when viewed from the top due to its high crown and deep pavilion.
  • Marquise Cut: Its elongated shape with pointed ends maximizes carat weight, making the diamond appear larger than it is.
  • Heart Cut: A symbol of love and affection, the heart cut is technically challenging to achieve and requires a high degree of precision.
  • Radiant Cut: Combining the brilliance of a round cut with the shape of an emerald cut, the radiant cut is known for its vibrant sparkle.

Where to buy fancy shaped diamonds? Whiteflash, Brilliant Earth, James Allen, and Blue Nile all offer great selections to choose from.

Each of these shapes has its own unique light performance and aesthetic. The cut of fancy shape diamonds is crucial and can significantly impact the stone's brilliance and scintillation. However, there's currently no universally accepted grading system for fancy cuts' light performance, making it essential for buyers to carefully review images and videos of these diamonds before making a purchase. With the recent acquisition of AGSL by GIA and the addition of the AGS Ideal Report, we may soon see more standardized grading of fancy shape diamonds based on their light performance.

Summary - Practical Advice and Conclusion

The cut of a diamond is arguably the most crucial aspect in determining its beauty, sparkle, and value. While carat weight, color, and clarity are significant, it is the precision of the cut that brings a diamond to life, enhancing its fire, brilliance, and scintillation. The cut influences how effectively light enters the diamond, how it interacts with the facets, and how it returns to the viewer's eye.

Given its importance, it's recommended to prioritize cut quality when purchasing a diamond. The round brilliant cut, especially those graded as 'Excellent' or 'Ideal,' is often a safe choice due to the high level of standardization and quantifiable light performance. Fancy shape diamonds, on the other hand, require a more careful and subjective evaluation.

Regardless of the diamond's shape, it's essential to review light performance images and videos. These can provide a better understanding of how the diamond handles light and highlights any potential flaws or asymmetry that may not be visible in the grading report alone. Tools like ASET images, Hearts & Arrows viewers, and Ideal-Scope images can be immensely helpful in assessing the cut quality of a diamond. Also, consider purchasing diamonds that come with comprehensive light performance analytics and detailed HD videos.

Embarking on your diamond purchasing journey? Head to Whiteflash for an unparalleled selection of the highest quality diamonds and designer settings. Whiteflash's commitment to quality, coupled with their extensive inventory, makes them the ideal choice for those seeking perfection.

For an impressive array of options at more budget-friendly price points, consider exploring Blue Nile and James Allen. They offer a diverse selection of high-quality diamonds, accommodating those with a smaller budget without compromising on the beauty and sparkle of your chosen gem.

Remember, choosing a diamond isn't just about price and size - it's about finding a diamond that represents your love story. Whether you're looking for the absolute best or seeking value for your budget, these trusted vendors will guide you to the perfect diamond that combines quality, beauty, and affordability.

In the evolving landscape of diamond grading, the merger of GIA and AGSL has led to the addition of the AGS Ideal Report, an addendum to the GIA grading report for diamonds meeting the stringent AGS Ideal cut grade standards. This is a welcome development, providing further differentiation within the GIA Excellent grade and introducing a more standardized cut grade for fancy shapes.

Lastly, remember that buying a diamond is also an emotional decision, not just a technical one. Choose a diamond that speaks to you and aligns with your personal taste and style. After all, a diamond is more than just a sparkling piece of carbon; it's a symbol of love, commitment, and the shared journey you're embarking on.

In conclusion, the world of diamond cutting is a blend of art and science, a dance between human craftsmanship and technological precision. The importance of understanding diamond cut cannot be overstated - it's what breathes life, light, and magic into these precious gems.