Cut of diamonds

The degree of cut of a diamond determines its brilliance. It is one of the 4Cs (Color, Clarity, Cut, Carat) and is the most noticeable of these four criteria. The higher the quality of the cut, the brighter and brighter it sparkles. Stones with a perfect cut beautifully highlight the special fire of a diamond.

Learn more about the grind level in the official GIA video (unfortunately currently only available in English).

Degree of cut in detail

The cut grade is a value used to determine the refraction of light of a diamond. When looking at the stone, the refraction of light is perceived as the sparkle typical of the diamond. When the cut proportions are perfect, the light coming from above the table is reflected by the individual facets of the diamond and directed upwards in parallel. If the cut is too flat, the light is directed downwards; if it is too steep, the light escapes to the side.

A perfect cut grade depends primarily on the proportions of a diamond, i.e. its ratio of height to width, table size to crown, crown to pavilion, number and angle of facets, arrangement and distribution of facets, as well as other specific influencing factors. This list shows how difficult it is for a cutter to achieve the perfect combination of all criteria and why only a very small proportion of all diamonds have the perfect cut grade.

Grinding grade EX

Excellent / Ideal

The highest level of polish. The proportions of such a diamond produce the most beautiful sparkle in a diamond. Extremely few diamonds achieve the perfect cut grade of “Ideal” or “Excellent”. Only just under 3% of all cut diamonds are awarded this cut grade. The incident light is reflected almost perfectly in the sense described above, giving the maximum possible brilliance and thus creating the unmistakable, unique sparkle of a diamond. Diamonds of this quality are something very special.

Grinding grade VG

Very good

As with diamonds with quality D, the color grade E is only awarded to exceptionally rare diamonds. Only a trained and experienced gemologist can identify the slightest traces of coloring. This color grade is therefore considered to be colorless.

Grind grade G


Diamonds with this quality feature still reflect the majority of incident light. However, the diamond's proportions are slightly less perfect than the two higher categories, so the cost is noticeably lower for the same size.

Grind grade M


Approximately 35% of cut diamonds have a “medium” cut grade. The quality of these stones is still good, but the brilliance of these stones is visibly lower than that of the higher quality levels.

Cut grade - P

Small amount

Diamonds with this cut grade do not meet Yorxs' quality requirements and are therefore not offered by us. The proportions of such stones deviate greatly from the ideal dimensions, so that almost all of the light entering via the table is directed to the side and across the floor. The brilliance of these diamonds is significantly reduced as a result; they do not have the fire typical of diamonds.

Cut and other diamond criteria

Diamond shape

For all other shapes except the round diamond shape (the brilliant), the cut is a much less important issue. It should also be noted that all other shapes have been less researched and assessing the cut is therefore more difficult.


Symmetry describes the arrangement of the facets relative to one another. The more symmetrical the facets are to each other, the more the diamond sparkles.


After the diamond is cut, the facets are polished. This can result in so-called polishing strips. These have a negative effect on the brilliance of the diamond.

Our recommendation for the degree of grinding

Since the degree of cut is one of the most important criteria for brilliant diamonds and has the greatest influence on the appearance of the diamond, Yorxs recommends that you choose the highest possible degree of cut - depending on your budget. The lower the quality of the cut, the lower the brilliance of the diamond and the less “sparkling” it will be.

In short: the stone loses “fire”. Diamonds that are used as an investment should have an excellent cut if possible. Therefore, please select a 3x excellent cut in the quality settings:

Degree of grinding: excellent
Symmetry: excellent
Polish: excellent

The cut of the brilliant

The examples and descriptions listed here primarily refer to the brilliant cut (round cut). For other shapes, certain rules may be slightly different, as criteria such as maintaining size and carat weight play a role in determining the type of cut and proportions.

With the quality of the cut and the assignment of the facets to each other, you can achieve the desired paths of light and the respective refraction of light for each reflection. Modern computer animation can now be used to show the light paths and show how complicated the light path in a diamond actually is. More recently, it has been proven that there are proportions of round brilliant cuts that deviate significantly from the fine cut in practice and can still result in maximum light output.

In any case, it should be noted that maximum reflection, i.e. luminosity and brightness of the stone, can only be achieved at the expense of light scattering, i.e. the sparkling, colorful play of colors of the stone, and that stones with the most lively, colorful fire are not at the same time the most radiant can be brightest. Since today people still want to see the colorful fire in the stone, the modern proportion is a compromise between the maximum use of the radiance (i.e. the luminosity) and the play of colors.

Hearts and Arrows

The appearance of a Hearts & Arrows pattern on round diamonds is a strong indication of an outstanding cut. Less than 1% of all cut diamonds have this quality. The pattern can be seen when looking from below through the pavilion with eight symmetrically arranged hearts and when looking from above through the panel with eight symmetrically arranged arrows. The hearts and arrows are usually not visible to the naked eye, but are only visible through a so-called “Firescope”, “Idealscope” or “Hearts and Arrows Scope”.

HRD and now also GIA, as the world's leading diamond certification laboratories, check this additional criterion for certain diamonds upon request and then show this separately in the corresponding HRD /GIA diamond certificate.

Yorxs recommends the highest possible grinding precision, Hearts & Arrows, which once again exceeds the normal 3-fold excellent grinding rating from HRD or GIA. The human eye perceives this maximum possible brilliance in direct comparison.


The processing of a rough diamond during grinding leaves traces, so-called polish streaks. These processing marks, in turn, influence the diamond's ability to absorb light and reflect it at the correct angle. Polishing streaks, possible scratches and scuffs can reduce the value of a diamond. Polishing is therefore also an important component in evaluating the cut grade. Completely avoiding these traces of processing is extremely rarely not possible. However, the fewer polish marks a diamond has, the better its grade and the higher its value. Only diamonds labeled Flawless (FL) have no polish streaks or residue.

Polish graduation

The polish is rated in five levels. The evaluation is based on a 10x magnification. Yorxs does not offer diamonds that are rated Poor in polish.

Excellent (EX)


No to marginal polish streaks, very difficult to see under 10x magnification.

Very Good (VG)

Very good

Very slight deviations in symmetry, visible under 10x magnification.

Good (G)


Deviations in symmetry, visible under 10x magnification, depending on the defects, may affect the brilliance of the diamond.

Fair (F)


Obvious deviations in symmetry, visible under 10x magnification, increasing likelihood of affecting the diamond's brilliance.

Poor (P)

Small amount

Diamonds with this symmetry do not meet Yorxs quality requirements and are therefore not offered by us. Strong deviations in symmetry, visible under 10x magnification, the brilliance of the diamond is visibly affected.


The proportions of a diamond are taken into account when evaluating the cut. The higher the cut grade of a diamond, the better its proportions are coordinated. The most important ratios for the cut are the relationship between depth and table as well as the thickness of the girdle and width of the culet. However, the perfect proportion per se does not exist. Different combinations of different aspects can lead to a perfect light reflection.


For round diamonds, the depth describes the ratio of the depth of the stone (distance between the table and the culet) to its diameter, which is measured on the girdle. For all other diamond shapes, the so-called “fancy cuts”, the ratio of depth to width is calculated. Depth is usually given in percentages. If the depth ratio is either too high or too low, then the diamond is too narrow, too wide, too high or too flat. If this is the case, the incident light is not optimally reflected and instead of coming out through the board into the viewer's eye, it emerges from the side or below. This causes the diamond to shine less. Diamonds with a particularly high depth can appear slightly smaller than diamonds with the same carat number but a shallower depth. This is because the lower part of the diamond is usually hidden when viewed from above. A depth between 59% and 62% is considered ideal for brilliants if the table is between 56% and 60%. Other depths, ie up to 59% and from 63%, may have larger or smaller panels due to proportionality. Please note that smaller deviations do not automatically lead to low brilliance.


The table describes the ratio of the table diameter to the total diameter of the diamond. The table is usually given in percent. As already mentioned, the table is a factor that is evaluated in the cut and has an effect on the brilliance of a diamond. This is because the size of the table affects the refraction of light in the diamond. Additionally, a large table usually makes a diamond appear larger. So when two diamonds with the same carat weight are visually compared, the one with the larger table usually appears larger overall. For brilliant cut diamonds, a table between 56% and 60% is considered ideal.

How are polish, symmetry and cut related?

The polish, symmetry and cut are closely linked. All three are largely responsible for how much the diamond shines and sparkles. Especially when it comes to diamonds as an investment, it is often recommended to buy so-called “Triple - X” stones. Triple-X or EX EX EX stones are diamonds with an excellent rating in cut, symmetry and polish.

Girdle / Belt (Girdle)

Girdle Thickness describes the height of the transition between the upper part of the diamond, the crown, and the lower part, the pavilion. The width of the belt also influences the brilliance, i.e. the radiance and shine of a diamond.

Belt graduation

The belt is usually described by English words (thin, thick, etc.). The belt of a high-quality diamond lies between the values ​​Thin, Medium and Slightly Thick. The belt is measured at the thinnest and thickest part of the girdle. On the detail page of each stone at Yorxs you will find information about the maximum and minimum width of the belt in the Details section. Extreme values ​​of the belt (round stone) have a decreasing effect on the value of the stone. Especially if both extremes are specified (e.g. belt minimum: thin; belt maximum: thick) this is negative for the value of the diamond. On the other hand, a girdle that is as even as possible increases the value (e.g. belt minimum: medium; belt maximum: slightly thick). Slightly thick or thick belts/girdles should always be faceted for good stones.

Extremely thin

Extremely thin

The girdle is practically wafer thin.

Very thin

Very thin

The girdle is very thin in many places.



The girdle is thin overall.



The girdle is balanced and medium strong.

Slightly thick

Slightly thick

The girdle is rather thick.



The girdle is thick.

Very thick

Very thick

The girdle is already very thick and strong.

Extremely thick

Extremely thick

The girdle is extremely pronounced.


The culet is another small facet on the lower part of the diamond (the pavilion), opposite the table. A diamond without a culet has a point-shaped tip. The wider the culet of a diamond, the less pointed the stone is and the more of the incident light emerges from the underside of the diamond. With very wide culets this can even be visible as a black dot in the panel.

Kalette graduation

The culet grade ranges from “None” to “Extremely Large”. A very good diamond has a grading between “None” and “Medium”.



Stone has a perfect point.



The tip is slightly blunted.



Stone has a perfect point.

Slightly large

A bit wide

The tip has a medium facet.



The tip has a large facet.

Very large

Very broad

The tip is very blunt.

Extremely Large

Extremely wide

The tip is extremely blunt.

our recommendation

When purchasing a diamond, you should not buy or rule out diamonds based solely on table and depth. The cut grade includes the proportions of the diamond in its rating and therefore it is easier and more sensible to choose the cut grade first. However, if you are unsure between two diamonds that have the same cut grade and the same other criteria, the depth and table can be used as an additional criterion to narrow down your choice.

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