Your Guide to Diamond Cuts

Your Guide to Diamond Cuts

Diamonds are hailed for their intense sparkle and magnificent shine. When we hear the term diamond cut, most of us conjure up images of diamond jewelry with stones of various shapes, from round to marquise. However, a diamond cut refers to how well a stone’s facets interact with light. While this is a common mistake, and most use the terms diamond shape and cut interchangeably, there is much more to understand. We'll take you inside a diamond's anatomy and why cut quality may be the most essential aspect affecting diamond quality.

What is Diamond Cut?

A diamond’s cut refers to its dimensions and how well-proportioned they are. Cut examines the stone’s facets or surfaces and how their positioning creates the stone’s brilliance, sparkle, and fire. 

The beauty of your diamond jewelry may be most determined by the quality of its cut more than any other factor. While all 4C’s of a diamond – cut, color, carat weight, and clarity – are vital to diamond quality, its beauty depends more on cut quality than anything else. Each precise cut magnifies a stone’s ability to reflect light through three critical components

Close up of top of diamond
  1. proportions: the alignment and placement of facets, creating overall shape or outline of the stone
  2. symmetry: a finished diamond’s arrangements and precise measurements of its facets
  3. polish: the quality of work on a finished diamond to achieve a glass-like surface and pristine smoothness

Why is Diamond Cut Important?

The cut of a stone is essential to overall diamond quality, as it determines each diamond’s performance. A well-cut diamond is a work of art, creating magnificent diamond jewelry pieces, as evidenced by its dazzling light reflection. The cut is responsible for influencing diamond quality through its brightness, fire, and scintillation

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  • Brightness refers to the total reflection of all white light from a diamond.
  • Fire describes the reflected light’s dispersion into colors of the spectrum.
  • Scintillation is the sparkle created from a diamond's movement as patterns of both light and dark areas are present.

Poor diamond cut may result in a lifeless, dull stone, regardless of its clarity and color grading. Diamond quality is maximized if the cut quality allows proper reflection and refraction of light.

Anatomy of a Diamond

Before we dive deeper, it may be helpful to get to know the anatomy of a diamond. Learning all the intimate details of a stone may help you appreciate your diamond jewelry pieces, as well as help you knowledgeably select future pieces for your diamond jewelry collection. Let's take a look at the diamond's various parts and terminology to help you understand the essential role cut plays.

Five Parts of a Diamond

A diamond is made up of five main parts that will help you understand how diamond cut and light affect its radiance. Having a bit of background on common terminology will also aid you in the remainder of our guide. The five diamond portions include:

  1. Table
  2. Crown
  3. Girdle
  4. Pavilion
  5. Culet

What is a Diamond’s Table?

Different color and shaped diamonds falling in front of black background

A diamond's table partially determines diamond cut quality. The table is the largest facet of a stone. The table refracts light rays and directs them to additional facets as they pass through the stone's center.

While we may love the saying bigger is better, this is not necessarily the case for your diamond jewelry. A diamond table that is too large may be hindered when dispersing light. The diamond's upper facets, located on its crown, will not have ample room to disperse refracted light brilliantly if the table is too large. Conversely, if the diamond's table is too small, its brilliance and overall diamond quality will be affected by its inability to let light in, to begin with.

What is Table Percentage?

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The physical size of a diamond’s table will vary from stone to stone. Table sizes may vary according to cut quality and overall size of the stone, as you may have noticed in your various diamond jewelry pieces. To ensure proper grading, jewelers measure by table percentage to yield a fair and accurate diamond cut grade.

To calculate table percentage, jewelers determine the ratio of the width of a stone's table in relation to the entire diamond's width. Naturally, ideal table percentages vary according to the shape of each diamond. These percentage differences may seem insignificant, but they can significantly impact the overall diamond quality. Ideal ratios may mean the difference between Good and Excellent ratings of brilliance and fire.

What is the Diamond’s Crown?

The crown of a diamond refers to the top portion of the stone. It is located below the table and above the girdle. Crowns may have brilliant-cut facets or step-cut facets. Crowns and their facets play a vital role in a stone’s light performance by:

  • driving the return of light
  • dispersing light, much like a prism
  • determining the level of brightness and amount of fire we see

What is the Diamond's Girdle?

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The girdle refers to the thin perimeter of the stone. It makes up the outer edge where the pavilion and crown meet. If you envision one of your diamond jewelry pieces, the girdle is the stone portion that is in direct contact with the setting. The girdle is the widest part of a diamond and is used to measure the total diamond perimeter. Diamond girdles do not affect the overall diamond quality or appearance and may be left rough, faceted, or polished.

Diamond Girdle Ratings

When diamonds become certified, various points along the girdle are measured in millimeters to determine its thinnest and thickest areas. Girdles are most often rated in ranges to explain the variance between these thick and thin points more accurately. However, both points may fall into the same category, resulting in it receiving a single rating. The Girdle Rating Scale includes ratings of:

  • Extremely Thin:The diamond may be prone to chips or breakage. Extreme care should be exercised when this stone is being set.
  • Very Thin:This diamond's girdle shows. There is good stone proportion, but care when setting should still be taken.
  • Thin, Medium:This rating reflects an Ideal gemstone proportion.
  • Slightly Thick, Thick:This stone's girdle represents “Excellent” to Ideal gemstone proportions.
  • Very Thick:The proportion of this stone’s rating is considered “Good".
  • Extremely Thick:Diamonds of this rating tend to appear smaller for their carat weight, as the girdle takes up much more of the diamond’s depth.

What is the Diamond’s Pavilion?

Single Blue diamond on its side

The pavilion connects the diamond’s culet and girdle, making up the bottom portion of the stone. The pavilion plays an essential role in a diamond’s light-reflecting properties. When a pavilion is cut correctly, it allows the maximum amount of light to reflect from the stone's surface. An excessively deep or shallow diamond can cause light to escape from the bottom and sides, reducing its sparkle.

While girdle diamond cuts on either end of the grading scale do not necessarily impact the stone's overall appearance, the differences between the thinner and thicker points on the girdle are considered in the diamond’s symmetry assessment. As you’re shopping for your next diamond jewelry piece, keep in mind that any significant variations may cause the diamonds to look disproportioned and of lower diamond quality.

What is the Diamond’s Culet?

The culet is the stone’s smallest facet and is found at the bottom of the diamond. All the pavilion’s facets meet up at this tiny point. Initially, the culet was intentionally cut to protect the stone’s pavilion. Today, diamond jewelry settings are generally created to be strong enough to provide ample protection to the pavilion.

Most diamonds’ pavilion facets are cut uniformly. These proper angles meet up at a perfect point, resulting in no culet, or sometimes referred to as a pointed culet. If the facets do not meet at a perfect point, the culet can be polished, rough, or faceted. Diamonds with a point will reflect a value of “None” under culet designation. A culet's presence will add one additional facet to the stone’s total number of facets listed.

The Effects of Diamond Culets

The lack of a culet is preferred in today’s diamond jewelry. However, culets were once widely used in Old European Cut and Old Miner’s Cut diamonds. Today, modern diamond cutting standards prefer to refrain from “Large” to “Extremely Large” rated culets, as they

Light hitting single diamond on a table
  • are visible through the table when viewing diamond jewelry from above
  • allow light to pass through the bottom of the diamond
  • cause the culet to mimic a dark circle

The presence of culets with “Small” to “Medium" ratings will give the appearance of a point at the stone’s pavilion base. Light reflects beautifully through these diamonds and makes them more desirable than most. While a pointed culet may seem the best choice, it’s important to note there are risks of chipping, both while being set and worn. In fact, some diamond cutters intentionally cut a small culet to minimize this risk.

Understanding Light and Diamond Cut

There are a variety of factors that play a vital role in a diamond’s brilliance. A stone’s ability to reflect light is the most essential. When light enters the surface of a diamond, A portion of the light is reflected through its table after entering the stone's surface. The light rays that remain continue traveling to the stone's center while bouncing off the diamond's internal walls. As the remaining light leaves the stone, dispersion creates colorful flashes, or sparkle. 

GIA’s Diamond Cut Grading System

GIA’s Diamond Cut Grading System is used to help determine the stone’s overall diamond quality, while each of the 4C's is assessed individually.  Based on a relative scale from Excellent to Poor, each cut grade reflects a range of face-up appearances and proportion sets.

Categories of The GIA’s Diamond Cut Grading System:

  • Excellent:Diamonds with this cut have superb craftsmanship. They emit a consistent pattern of dark and light areas, demonstrating brilliance and light dispersion. Diamonds classified as Excellent are of superior diamond quality.  
  • Very Good:The most commonly sought-after cut, this stone provides great diamond quality at an exceptional value. Stones with a Very Good diamond cut rating have a high level of craftsmanship, dispersing a very good amount of light and brilliance.  
  • Good:Stones placed in this diamond cut category disperse a good amount of light, although its scintillation is not quite as brilliant.  
  • Fair:Stones with a Fair diamond cut assessment have an average level of scintillation, offering a lack of contrast. This diamond cut generally appears darker, only emitting a fair amount of light.  
  • Poor: Diamonds of Poor cut reflect a low level of craftsmanship. They cannot adequately disperse light and brilliance.

What is Diamond Depth?

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As with a diamond’s table, the depth also helps define a stone’s physical shape. Table and depth increase diamond quality by contributing to its radiant sparkle. So, what is diamond depth, and how does it directly affect your diamond jewelry?

Diamond depth, sometimes referred to as height, is calculated by the distance between the stone’s table and its culet of the diamond. As with tables, jewelers grade each stone’s depth based on its depth percentage. A diamond’s depth is divided by the width of the stone to calculate its overall proportions. These percentages play a significant role in how light is reflected off the diamond's facets, signifying diamond cut quality.

How Does Diamond Depth Affect Diamond Quality?

We all want our diamond jewelry to possess that wow factor. Understanding how depth may impact diamond quality can help you make an educated decision when selecting your next diamond jewelry piece.

A diamond’s depth impacts overall diamond quality by contributing to its sparkle appeal.  Stone cuts may be classified as shallow, ideal, and deep, affecting sparkle and overall appearance. Let's take a closer look at the differences in-depth:

•       The Shallow Diamond Cut

If a stone’s cut is too shallow, the light will enter the diamond only to escape through the pavilion. Shallow cut diamonds are unable to reflect light for this reason and lack brilliance while decreasing diamond quality

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•       The Ideal Diamond Cut

This cut is considered the premier diamond cut style. It offers well-proportioned and precisely angled cuts to achieve exceptional diamond quality with optimal performance and luminance.

•       The Deep Diamond Cut

When a diamond cut is too deep, it tends to make the stone appear much smaller than other diamonds of similar carat weight. Deep diamond cuts yield poor diamond jewelry sparkle and appeal.

Diamond cut knowledge is essential in making an investment that meets your wants and needs. As you shop for your next diamond jewelry piece, whether it be an engagement ring, bracelet, or Rolex watch, you’ll be more than prepared to make the best selection.