Diamond Cut - 4Cs for Measuring Diamond Quality

No diamond worth its value is ever complete without being the beneficiary of a great cut. The reason why the quality of the diamond cut is such an integral part of assessing the stone's value is that diamond prices vary with respect to the type and quality of the cut. Diamonds in the world of jewellery are naturally viewed in association with the type of cut in question; as the type of diamonds we are engaging are the ‘cut’ and polished variety: meaning diamond which is not rough. This is an important distinction to keep in mind. Diamond cutting is a key part of the fine jewellery and gem business, that does not, like anything that pertains to gemstones, operate alone. Since the quality of the diamond cut works with other key variables that determine diamond quality: Carat, Clarity, and Colour. In this post we learn about the factors that affect a diamond’s cut; the aim of diamond cutting, the qualities of cuts and the key factors that a diamond cut. First, let us break down two-three key factors (or diamond superpowers) that you need to keep in mind when studying diamond cut: Brilliance Fire, and Scintillation.

Fire

Think of a diamond fire as its ability to produce a rainbow-like colour effect. Whilst fire and the rainbow may not be of the same character, know that both originate from a single light source: the Sun. A diamond’s ‘Fire’ also known as ‘light dispersion’, describes the flashes of colour that a diamond is able to disperse under lights. The prism-like lighting effects result when white light is broken into the various colours in the spectrum as it hits the gemstone. Diamond fire-the rainbow-like colour effect- is interestingly not unique to this precious stone. However, this effect reaches, arguably its greatest prominence in diamonds. Whilst the display of fire in diamond occurs in all variants of this gemstone, however, the strength of this effect differs from diamond to diamond and is a feature that is greatly affected by the quality of its cut.

Brilliance

Arguably the most notable element of the diamond: Its brilliance refers to a combination of effects that helps affect how white light is able to emit out from the diamond, but essentially in its white or undispersed character. A poor diamond cut will mean that white light, which is a key indicator of the diamond's visual quality, will leak out of the pavilion (lower part) of the stone, rather than glowing from the crown (top of the stone). So there is a balancing act at work. For whilst the breaking of white light and the emergence of colour within a diamond is valued for its own sake, when it comes to its brilliance, the key factor is the diamond’s ability to transmit the white light that enters it.

Scintillation

Think of scintillation as the effects caused by light in motion in the diamond. Which is affected by the movement that the diamond is subjected to, causing distinct patterns of dark and light that emanate from its facets. Scintillation is produced by the contrasting effects of the light and dark that are determined by their facets. Each of these factors is affected by the nature and quality of the diamond’s cut.

The Grading of a Diamond Cut- GIA

A Diamond cut, depending on the quality of the process, would differ in terms of its final quality. The GIA has put in a place a strict framework that assesses the quality of the diamond’s cut. The key factor is the ability of the cut to increase the ability of light to enter, interact and emanate from the diamond. According to this standard, a diamond cut is graded according to 5 levels.

Excellent	Excellent Cut diamonds are at the top of the list, as these provide the greatest level of fire and brilliance. The quality of the cut ensures that virtually all of the incoming light that hits the stone is reflected through the table (the top surface of the diamond), and thus carry a much greater sparkle.
Very Good	Very Good Cut Diamonds also score high in the brilliance and fire scales. This cut enables a considerable level of light that hits the diamond to be reflected through the diamond’s table. Without the aid of expert tools, diamonds in this category emanate will almost equal in terms of sparkle to those of the Excellent grade.
Good	Good Cut Diamonds carry a great degree of brilliance and sparkle, with a high-level light being reflected through the table. However, the intensities of the light reflecting attributes are noticeably lesser than those above in the grading scale. These diamonds provide value at a lower price owing to the lesser quality of the cut.
Fair	Fair Cut Diamonds come at the lower end of the scale, and hence offer a lower level of brilliance; this type of cut, permits light to easily leak out of the end and sides of the diamond. Diamonds that qualify as ‘Fair’, are diamond cuts that graded are for their acceptability for those seeking a budget option, or to serve as an accent stone.
Poor	Poorly Cut Diamonds, which are at the bottom of the list, thus yield nearly no sparkle, brilliance or fire. The diamond of this grade of cut has poor light interacting abilities.

Factors that affect a Diamond Cut

Diamond cutting is a delicate process. One that is carried out by qualified experts in the field, requiring great care, knowledge of many factors that affect the gemstone’s quality, and critically, such as the need to maintain a larger carat stone. Gemologists and jewellery experts who work in diamond cutting consider three important factors when it comes to this process, factors that affect a diamond cut and by extension its value.

Polish

This factor is a bit more on the subjective side when it comes to determining the quality of a diamond cut. Diamond polish determines the quality of the stone based on how well a diamond’s polish works to accentuate the quality of the cut. So diamond cut, with its respective shape and facets, the polishing process is essentially the finish to the gemstone. However, the polishing process is not a straightforward one, as the cut of the diamond places obstacles to this stage, as the jeweller needs to carefully navigate these edges, to ensure that the quality of the cut is not affected by the polishing. As the process of polishing tends to generate marks or other inconsistencies on its surface, which needs to be minimised for optimal results. Which is key in ensuring that you get your hand on a quality diamond engagement ring.

Symmetry

Arguably the most important factor when it comes to measuring the value of diamond cuts, symmetry deals with how precisely the various facets of a diamond align and intersect to produce a uniform shape. Many things impact a diamond’s symmetry: its facets, crown angles, its crown height, the location of its culet, its pavilion angles etc. The diamonds that score highly on the grade for symmetry, are those that have the correct number of facets and contain little or no symmetry variations. Symmetry is important since the correct alignment of the sides and angles of the diamond ensures that light is reflected in a correct and uniform way. Diamond cuts with poor symmetry, with defective sides, will mean that light will emit in a non-uniform way. The quality of the symmetry deals with the quality of the cut, which we shall get to.

Quality of Diamond Cuts

Another key determinant of a diamond cut’s quality is the proportions of the diamond, that work into its overall structure. Diamonds that are proportionate and align correctly on all sides, in terms of their height, width, and length are measured according to three levels of quality:

Shallow

Shallow cut diamonds are cut in a certain way make them seem broader on the sides, but with the pay off being that the diamond lacks the required depth to give it a desirable proportion. Further the larger middle whilst creating the illusion of larger size sacrifices the ability of the diamond to reflect light. As a rule, in the world of diamonds and gemstones in general, whenever a cut deviates from the ideal proportions, some of the beauty, with respect to its brilliance and sparkle, which are related to its proportions, of the diamond is lost.

Deep

Deep cut diamonds differ from shallow cut ones but do so by going in the opposite extreme direction. The depth or the height of the diamond deals with the distance from the stone’s table to its sharp end of the diamond. The main downside of this cut is that it overcompensates in attempting to provide a keener shape, and weakens the ability of light brightness to interact with the surfaces of the diamonds. Diamonds with deep cuts also pose problems when mounted within fine jewellery, as the leaner shape, owing to the smaller girdle produced by this cut, makes the stone seem smaller in size than usual.

Ideal

Ideal cut refers to a diamond-cut where the proportions of the precious stone: with the depth and the average diameter of the girdle of the diamond are aligned well, without overcompensation to other levels, so as to help manifest the greatest level of brilliance and sparkle, whilst maintaining the overall consistency of the diamond’s shape. Unsurprisingly, ideal cut diamonds are the most optimal, and the most sought after in the world of gemstones. The closer the diamond cut is to the ‘ideal’ standard, the greater its value and price. Of course for those who find the process of diamond buying a bit too complicated, know that there is always the white sapphire option available for you, or maybe a ring that combines both gemstones!