The Diamond Cut Guide: Most Popular Cuts & Grading Chart
The Diamond Cut Guide: Most Popular Cuts & Grading Chart
Posted by Sharif Khan on 21st Jun 2022
The cut is often considered the most crucial aspect of buying a diamond. It refers to the brilliance of a diamond and determines how light is reflected through it. However, it should not be confused with its shape, which refers to the general outward appearance.
A good cut will allow the light to travel through the stone and reflect from side to side. The light then reflects off the stone, which you can see with your eyes. In diamond terminology, this sparkle is called "brilliance."
Crafting jewelry by cutting diamonds is a delicate and highly regarded work. It is both science and art—science in that certain angles must be precisely followed based on proportions and art because the final shape must exude a high-class beauty.
The Cut of a Diamond is Important
The diamond cut is perhaps the most critical factor in assessing brilliance and fire. Given that it is the only C that is not a natural but a human factor, it can be manipulated to save rough parts while cutting a diamond. The Gemological Institute of America (GIA) has developed a comprehensive system for assigning cut grades to round brilliant-cut diamonds. However, it has yet to be finalized for fancy-shaped diamonds, such as the cushion or Asscher cut. The cut range is from Ideal/Excellent to Very Good, Good, Fair, and Poor. For example, since non-round-shaped 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 it is cut—follow this guide for an oval cut diamond. The most important factors to consider while assessing a diamond's cut include the depth, table, girdle, crown angle, pavilion angle, and culet. You should pay attention to depth because it can be substantial at times, making a 1-carat diamond look like a 0.7ct. Please follow our diamond proportions guidelines for precise information on each shape.
How GIA Cut Grade System Works
The GIA Cut Grading System for brilliant round diamonds is defined and allocated one of five cut grades: poor, fair, good, very good, and excellent. It is based on predictive metrics and the observation and computer modeling of diamonds' appearance. With the help of a prognostic computer model, the system estimates the beauty and brilliance of diamonds based on interrelated specifications.
The GIA cut grading is based on the evaluation of seven elements. Scintillation, brightness, and fire are based on appearance, while the other four rely on craftsmanship and design, such as weight ratio, polish, durability, and symmetry.
Here is an outline that will help you understand the GIA's cut grading system and what differentiates an excellent cut from a good or fair one.
- Excellent grade: This category has high scintillation, brilliance, and an even pattern of dark and light areas.
- Very good: Despite high scintillation and brilliance, diamonds in this grade are darker in the edges or center. Notably, a diamond can sometimes have a higher scintillation and brilliance, but its pattern will lower the grade
- Good grade: This category is slightly dark and has lower scintillation. A diamond's weight ratio or pattern can be downgraded.
- Fair grade: A gem in this grade has slight scintillation and brilliance.
- Poor grade: Gems in this grade have inferior proportions and display slight scintillation or brilliance.
Understanding the attributes of diamond appearance
Here are some elements that make up a cut and how it affects a gem's appearance.
It refers to the quality of diamond facets due to the polishing procedure or the blemishes left after the cutting procedure. Polish elements are situated on the surface and do not visibly penetrate the gem when viewed at 10x magnification. It is evaluated on a scale comprising excellent, very good, good, fair, and poor. Most diamonds have imperfections since craftsmanship mistakes leave polish marks. Hence, their facets must be carefully polished at the end of the cutting procedure to minimize errors.
Perfectly-polished diamonds must have excellent smoothness and exceptional regularity to ensure they do not 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. Thus, 14 dead spots in equally set-apart three-D areas can cause the facet to be non-polishable. The dead regions are often situated on the cube and octahedron faces. For fire and brilliance to not be affected, cutters must ensure that the facets do not coincide with the dead spots. Artisans can move the facets, which make up the symmetry, so that they can shine.
Diamond symmetry is the alignment and appropriate positioning of its facets. A professional artisan will set each facet in proportions that complement the surrounding facets. The placement must be completed professionally since the facet junction that does not align will make the stone look uneven. Moreover, the symmetrical quantity of a perfectly cut diamond will deter excessive carat weight in the profile. This makes the gem look heavier than it is.
Additionally, the alignment of facets will define the stone's interaction with light. Some light that hits the stone immediately reflects as a surface stare. A portion of the light that gets into the stone escapes via the bottom and does not visually impact the viewer. A very shallow or deep cut will let light leak from the diamond's internal wall or crown, making many facets dull or dark. As a result, the general appearance will be less sparkly and brilliant. Conversely, appropriately placed facets can maximize the amount of light reflecting from refracts or tabletops and bouncing off the internal walls into an observer's eyes.
The visual impacts of the external and internal interactions with graying light establish the brilliance of a diamond. Scintillation will be caused by an equal balance of light and dark spots, creating a clear pattern with no distracting dark outline. Once the light shows in the gem, it causes fire
as it is dispersed into the rainbow of shadows like colors. If the light source, the 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 separating the pavilion from the crown and works as the stone's setting edge. It reduces the risk of damage when adequately thick, comprising 16 hill and 16 valley positions formed by the final cutting. An optical gadget calculates the average thickness and percentage using the available formulae. Therefore, the maximum and minimum verbal descriptions depend on the decisions 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 are measured via the non-contact optical measuring gadget. With the GIA multipurpose gemological reticule and microscope, you can also measure it. Girdle thickness evaluation depends on visual observations because the measured outcome results are vulnerable to the variability inherent in measurement gadgets. This also holds when differentiating between very thin and exceptionally thin girdles.
Diamond culet size
A diamond culet is a tiny spot beneath the pavilion where the latter and the facets meet. In many stones, the pavilion facets are uniformly crafted at the right angle and close at the perfect point, leaving 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 to the stone's cumulative number of facets.
- Culet size rating
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 culet's size and sideways to define its angle. A sharply angled culet is not evaluated as a culet but as an additional facet. Diamond culet size is expressed as a percentage relative to the diameter for approved diamonds, with culets ranging from small to extremely large.
Here is a description of culet size:
- Note: Since there is no space beneath the pavilion, light cannot escape the culet and is bounced back. It is a requirement for well-cut grade diamonds.
- Very small: The culet comprises a tiny opening that is invisible without magnification. Since light seepage is reduced, it cannot affect the gem's light performance and sparkle.
- Small: This culet has a noticeable opening that leaks some light under magnification. However, the diamond will have incredible sparkle and high brilliance.
- Medium: A visible opening is noticeable under magnification, though 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, affecting the brilliance of the stone.
- Very large: A vast opening is available in the stone. You cannot see the brilliance of the stone's cut.
A crown serves as a window that drives light and defines the brightness of the stone. It also acts as a prism that disperses light, giving the crown facet size, fire, and angel. This will help you define the amount of fire the diamond releases. The crown facet also curvatures 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 is the same as the crown height. Therefore, a higher crown means a greater angle. Most diamonds have crown angels that range from 25 to 35 degrees. Diamonds whose crown angles are more shallow than 25 degrees tend to be bright, but they are more vulnerable 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, surrounding the gem with a rim of precious metals. Shallow stones are ideal in jewelry where they are not susceptible to damage. The craftsman who cuts diamonds from rough attempts to achieve the largest girdle diameter and high weight retention. Therefore, they are usually cut with shallow pavilions and crowns and have a large table percentage and thin girdles.
- Ideal crown angels
The crown angle compensates for the bending light caused 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 a crown angle that maximizes the proper return for any designated pavilion angel.
Experts calculated that the perfect crown angle is 34.5 degrees paired with a 40.75-degree 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 does not bend light correctly, you will need a shallower crown angle of 43 degrees to compensate.
The pavilion angle
The lower girdle facet and pavilion are mirrors, and their reflective index defines a stone's ability to work as a mirror. The reflective index represents 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 hits at a perfect angle greater than its acute angle.
A pavilion angle is vital in determining whether a diamond is proportioned correctly or if the stone will require re-cutting. In addition, the table reflection technique helps identify the pavilion depth/angle when it comes to mounting. In most cases, a space in the mounting under the culet allows a direct measurement of the entire depth.
If the general depth of a pavilion is greater than 63 percent with a shallow crown, it is considered deep. For instance, visually, you can identify a flat crown by looking at the stone's side profile and a normal or medium girdle.
- Ideal pavilion angles
40.75 degrees is the ideal pavilion angle, according to mathematics professionals. Interestingly, artisans cut the stones at this angle before it was defined. Diamond cutters claim that beyond 41 degrees, it is too steep. Retailers selling badly cut stones will lure you by saying that a cliff of 41 degrees is ridiculous. However, according to physics, there is a critical angle before light escapes. Hence, what takes place is not a cliff, but a smooth transition from stronger to weaker light as more rays escape.
The aspect you need to remember is that the transition happens around 41 degrees. Therefore, unless you find a super-ideal gem cut at 40.9 degrees, you are good to choose something close to 40.75 degrees. While using light ray tracing, researchers have found that a pavilion angle of more than 40.5 degrees is exceptionally shallow and will result in light leakage and obstruction.
Painting and Digging Out
Printing and digging out refer to the faceting methods for the half facet that influence the stone's three-dimensional settings. They include the relative position, horizontal angles, and distance from the center of the stone. The painting and printing methods are applied to save the stone's weight during the cutting procedure. They get rid of attachments near the girdle or influence the face-up appearance of the gem. You must note that painting and digging out methods on cut grading are affected by the virtual distinguishability of the techniques and if the pavilion or crown or both utilize them.
More about Diamond Cuts
Diamonds must be cut to get a shape; their actual cut refers instead to their 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 into 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 slowly but surely making a comeback because it has an old-fashioned look that people like today.
The amount of light and the way it exits a diamond depends on the type of cut and is often referred to as the quality of the cut. For instance, if the cut is too shallow compared to its width, the light will directly exit the diamond with little to no reflective qualities, making it appear dull and lusterless. Likewise, if the diamond's cut is too deep, the light will escape from its sides rather than through it, leaving the stone 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 so that it encompasses the entire diamond and allows for maximum brilliance and radiance. A cut's quality can be signature ideal, ideal, very good, good, fair, or poor.
Diamonds are cut from stones in various shapes known as cuts. While most stones can be cut into any of these shapes, the diamond's natural shape and qualities determine which shape is chosen for the best effect. If you are custom designing your diamond jewelry or shopping for an already designed piece, you should understand the terminology used to describe the different cuts used for diamonds. The term "cut" refers to the shape of the diamond when viewed from above.
The diamond cut is one of the most critical aspects in attributing value to a diamond and can sometimes account for up to one-third or more of a diamond's appraisal. It is generally so because certain cuts waste more of the raw diamond in the cutting process than others—diamonds that waste more cost more.
In addition to the shape, different cuts affect how light passes through a diamond. In this way, how a diamond is cut will also determine its brilliance and sparkle.
MOST POPULAR DIAMOND CUTS
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 diamond sides are faceted to allow the light to reflect across the diamond center, creating the fire and sparkle that is the hallmark of beautiful stone. Round diamond cuts are trendy for solitaire-style rings and are ideal for stud-type earrings.
2. PRINCESS Cut Diamond: The princess cut is another widespread diamond cut for the large or center stone or in a solitaire style. This cut is the square to rectangular cut seen in many antique and modern settings. Diamonds used for the princess cut must be superior in clarity to prevent the color from showing at the cut's points or corners.
3. Cushion Cut Diamonds: A unique diamond shape makes for an exciting 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 a statement in a solitaire engagement ring setting.
4. EMERALD Cut Diamond: The emerald cut diamond 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 clear, high-quality diamond to preserve its clarity.
5. ASSCHER Cut Diamond: A less common cut is the Asscher, a square version of the emerald cut. The difference between the Asscher and emerald cuts is that the former (Asscher) is square rather than rectangular. This cut is not traditionally chosen 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 older and more modern settings and can be accentuated with baguette-style diamonds or gems.
7. PEAR Cut Diamond: The pear shape is like the marquise but with one end rounded and the other pointed. This diamond cut can add a slimming and elongating effect to the ring finger and is considered one of the classic diamond shapes. Pear-shaped diamonds are also famous in earrings and necklaces, where they give the impression of length.
8. Radiant Cut Diamonds: These are versatile with their square shape and trimmed corners. This cut combines the classic emerald shape with the brilliance that nearly matches a round-cut diamond. It is quite similar to the princess cut but is usually slightly more in the shape of a rectangle, having its corners blocked.
9. HEART Cut Diamond: Heart-shaped diamonds are considered the ultimate and most romantic of all diamond shapes. Besides its shape, the skills required for a diamond cutter to bring out a diamond's natural brilliance and create the smooth profile of a heart determine its value. The heart diamond cut makes for an excellent engagement ring with its tapered point and rounded lobes.
10. PILLOW Cut Diamond: The pillow cut combines the round and princess cuts with lots of facets, resulting in sparkle and fire. The cushion cut is one of the most common cuts on antique diamonds and is very popular in pendants and other large settings.
11. Oval Cut Diamonds: As the name says, it is oval and the closest to the round cut diamond. This cut features a flattering, more extended outline that combines with the brilliance of a round-cut diamond. Additionally, these diamonds are popular engagement ring choices because their length can accent longer, slenderer fingers.
CHOOSING THE BEST DIAMOND CUT
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, other diamonds will have some similarities in characteristics. Only a few 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 use their licenses to create similar cut diamonds and sell them at cheaper rates. This problem has been complicated because there is no final industry agreement on how diamond cuts are named. Another issue when buying diamonds based on cuts is that each will be defined with some personal touch. Famous cuts in different regions reflect these kinds of preferences.
1. Check the grade of how the diamond was cut. Look at the diamond-grade certificate to find better stones cut into better forms. Only stick with the "Excellent," "Very Good," and "AGS0" grades.
2. After collecting your prospective diamonds, examine this shortlist by putting them under different light conditions. Grading laboratories and companies use fluorescent lights for grading their stones. Unfortunately, this unfavorably affects the diamond's appearance. Hence, try viewing the diamond under several fluorescent and incandescent lights and direct sunlight.
3. Doing this will surely help get the feel of the diamond's personality. You can figure out how each cut changes the stone's fire and brilliance by comparing your shortlist to those of other people.
4. Always have the final say when diamond shopping and decide 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.
Generally, the more depth a diamond has, the more brilliance it will have. To calculate a diamond's depth percentage, divide depth by width and multiply by 100. Before a diamond is cut, the diamond cutter must analyze the diamond. Two factors are important: maximizing the investment return and how fast the diamond can be sold. For maximizing the return on a diamond, the cut is essential. The cutter has to look at several factors, such as weight and color retention, the shape of the rough stone, and the location of inclusions and flaws.
Diamond cutting involves four methods: cleaving, sawing, bruting/cutting, and polishing. Cleaving is the first step in diamond cutting and comprises reducing a rough diamond to a manageable size using wax or cement mold. Next, the cutter cleaves the diamond along its weakest point, called the tetrahedral plane. Sometimes, 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 bruising or cutting to give it its shape. When diamonds are cut by hand, it is called "bruting," while cutting is done using a lathe. In either process, one diamond is used to cut another. After the diamonds are cut, the cutter uses a rotating polishing wheel coated with an abrasive powder to finish the diamond. When a diamond is cut, 50% of it can be lost. Lastly, because many qualities of a diamond depend upon its cut, the cutter's skill is vital.
The cut of the diamond stone should not be your only basis when buying a diamond. You should consider other important factors, such as how the price will fit into your budget. Furthermore, before deciding which diamond cut to go with, consult reputable experts in diamond cutting and check the polishing.