The beauty of the stone hinges on the cut quality factor more than it does the other C’s. That should make it easy for buyers to choose the Perfect stone but grading on cut is an extremely trying and difficult process. It is the only factor at the hands of the cutter and as much as they try to precisely adhere to set parameters, mistakes are bound to happen. After all, the craftsman is treading a thin line between maximizing on carat weight and optimizing on overall appearance. The big question, however, is whether the inaccuracy of the cut can be deemed an error if it still boasts the brilliance, sparkle, and fire of the stone? To complicate the difficulty of grading cut even further, diamond connoisseurs argue that there is no magical combination of diamond proportion that yields the Perfect Cut. Nonetheless, in determining why cut rules over color we must put in the limelight all the elements that make up a ‘cut’ as well as how the components impact the diamond’s appearance.

Diamond Cut Symmetry

The symmetry of a diamond refers to the alignment and proper positioning of its facets. A good craftsman will expertly place each facet in appropriate proportions that complement surrounding facets. The positioning of the facets should be done with expert precision because facets junctions that don’t align make the diamond appear uneven. Furthermore, the symmetric proportions of a well-cut diamond are what deters excessive carat weight hiding in the profile. Making the stone appear just right for its weight.

The alignment of the facets also determines the stone’s interaction with light. Some of the light that strikes a stone immediately reflects as surface glare. While a portion of the light that enters the diamond escapes through the bottom having no visual effect to an observer. A too shallow or too deep cut allows light to leak out through the crown or the diamond’s internal walls making many of the facets appear dark or dull and the overall appearance is less brilliant and sparkly. Properly positioned facets maximize the amount of light that bounces back (reflects) from the table top or bends (refracts) and bounces off the internal walls to an observer’s eye.

The observable effects of the internal and external interactions with white light are what constitutes the brilliance of the stone. Scintillation will result from an equal balance of dark and light areas forming a crisp clear pattern with no distracting dark outlines. As the light exits the stone, fire results from the light being dispersed into a rainbow of spectral colors. If the light source, diamond, or the observer moves, spots of light that flash (sparkle) will be noticeable.

Diamond Cut Polish

Like symmetry diamond polish is a vital component of cut quality. Polish refers to the precise condition of diamond facets. Very few diamonds have no imperfection due to polish because unlike inclusion which occurs naturally, polish marks result from craftsmanship error. To minimize flaws, every facet of the diamond should be carefully polished at the end of the cutting process. A stone is well-polished if it has exceptional smoothness and excellent regularity such that it is free of nicks, burn marks, polishing/ wheel marks, abrasions, and lizard skin. However, diamond surfaces are anisotropic, meaning that there are softer and harder zones. As a result, there are 14 areas (dead spots) at equally spaced three-dimensional zones that would cause the facets to be unpolishable. Usually, the dead spots are found at the octahedral and cube faces. To ensure the brilliance and fire of the stone remains unaffected, cutters try to ensure that none of the facets coincide with these dead spots. The craftsman can go as far as to move facets, which compromises the symmetry, to ensure that all cut facets can be polished.

Diamond Cut Proportion

The proportions of a diamond directly affect its interaction with light which ultimately determines the overall appearance of the stone. That’s why it is crucial that the depth, table, and width are in the correct proportion. It is important to choose GIA certified diamonds for consistent grading report.

Depth

The depth of a diamond is the distance in millimeters from the table top to the culet which is the entire stone’s height. By dividing the depth by the diamond’s diameter, the result is the depth percentage. Generally, the higher the depth percentage the lower the optical illusion of a larger face-up appearance in diamonds of the same carat weight.

When light strikes a diamond, the depth plays an intricate role in determining how the interaction with light plays out- reflection or refraction, which in turn affects brilliance and sparkle. Therefore, a stone whose pavilion facets are in correct proportions allows light to be refracted within the diamond and reflected out at angles in line with an observer’s eye. Increasing the beauty of the diamond by making it appear more sparkly and masking imperfections. Incorrect depth percentages lead to unattractive fish-eye effects and undesired dark nail heads. Like in all the other diamond proportions, the ideal depth percentage varies with the shape of the stone.

Table

The diamond’s table is the largest flat surface at the top of the stone while the table percentage is the ratio of the width of the table to the width of the stone. The overall brilliance and sparkle of the diamond are directly affected by whether the table percentage is in correct proportion to the depth of the diamond. For a stone with very low table percentage, when light strikes the table it becomes trapped within the stone and emitted through parts of the diamond that are unlikely to reach the eye such as the culet. A larger table percentage also negatively impacts interactions with light as reflection will not occur on the stone’s facets and crown angle. Instead, the light will escape from the crown and the brilliance and fire of the stone will greatly reduce.

Width

A diamond’s girdle is the measurement from one end of the diameter’s widest point (girdle) to the other end of the girdle. The width is important because it is factored in the calculation of table percentage and depth percentage which impacts the appearance of the stone.

 

Table percentage = width of the table / width of the diamond

Depth percentage = depth / width of the diamond

 

Bear in mind that there is no magic combination of percentages that gives the perfect diamond. The calculations are used as a guideline for filtering undesirable from one’s choices.

Diamond Cut Grade

The cut grade of a diamond takes into account the combined effect of the alignment and positioning of facets, table, and depth proportions, as well as the degree of polish and symmetry. The intricacies of proportioning may not be apparent to the eye but the overall beauty and sparkle act as a telltale sign. Other than appearance, diamond cut grade also reflects on whether the cut is shallow, deep, or just right. An ideal cut will have almost all the light reflecting or refracting back to an observer’s eye to give a stunning brilliance and lively fire.

Cut or Color

Yes, diamond color is important but it is not as significant as cut quality. In the diamond industry, there is a marked preference for colorless diamonds. What few people know is that an excellent cut will mask the yellowish tint in a near colorless diamond while the most colorless diamond cannot hide the dullness of a poor cut grade. Moreover, the differences in color grades are so small such that to the untrained eye the discrepancy is none existent. But because colorless diamonds are so rare, the color grade has a significant impact on the price tag with diamonds at the top of the color scale being sold at astronomical prices.

To assign color grades, grading labs follow strict guidelines that dictate the kind of neutral backgrounds and type of lighting used as well as how the diamond is held and viewed throughout the assessment. The diamond is placed down and its color compared to a set of color-comparison stones known as master stones, whose color grade on the D-Z scale is known. Viewing the diamond from the culet reduces the multifaceted appearance of a faceted colorless to near-colorless diamond when viewed from the table top.

Color is also subject to personal preference while cut grade never goes out of style because it has the greatest impact on the overall beauty of the diamond. Who wouldn’t want that stop in your tracks stunning brilliance and lively fire of a well-cut diamond?