Diamond Education

Cut

A Diamond’s Cut Unleashes Its Light

Whilst a diamond’s Colour and Clarity are created by nature, the Cut is determined by the Gem Cutter and is the only factor impacted by human intervention. The Cut grade is the most complicated of all the 4 C’s as it considers the face-up appearance of the diamond, the design – weight ratio, girdle thickness and durability – and the craftsmanship for polish and symmetry. With so many variables to consider and no two diamonds alike, you can see how this can be a complex but important factor to examine when purchasing a diamond.  

The face-up appearance is based on the attributes relating to brightness, scintillation, and fire. Essentially, how well the diamond reflects light throughout the stone. A diamond’s proportions – its crown and pavilion angles and the measurement of the facets – will determine how well the diamond can reflect or disperse light back to the wearer’s eye. In a well-cut diamond, light enters the table and travels through the stone reflecting from one side to the other, using the tiny facets as mirrors, before the light is directed back to through the top of the stone. 

A shallow-cut diamond will cause light to escape through the bottom, while a deep-cut diamond misdirects light through the side. These negatively impact light reflection; the brilliance and the sparkle we have come to expect from a diamond. 

The design of the diamond, its weight ratio and girdle thickness are important to ensure the diamond appears to the wearer, as the weight would indicate. A diamond with a greater width-depth ratio may appear larger face-up, but the reverse is true if the stone carries more weight in its depth, and less across its width measurements. Likewise, a diamond with too much girdle thickness can hide unnecessary weight, making the diamond appear smaller when viewed face-up. Ultimately, a diamond should look like its weight indicates. A 1-carat round brilliant cut diamond should measure 6.4mm across from girdle to girdle. If it doesn’t, the width-depth ratio may not be ideal. 

Durability is a factor when the diamond may have been cut with an extremely thin girdle, which can make the diamond susceptible to damage during setting or heavy knocks. Checking your diamond certificate for the girdle thickness can assist you in avoiding this potential pitfall.  

When determining the cut grade, all five characteristics – brightness, fire, scintillation, weight ratio and durability are considered and individually rated as excellent, very good, good, fair, or poor. The diamond is given an overall grade based on the lowest grade received across all factors. If any one factor is graded as poor, the overall cut grade will be poor. Similarly, all five must be graded as excellent for a diamond to be given an excellent cut grade. 

The craftsmanship of a diamond, its polish and symmetry are the other two characteristics assessed when a diamond is certified. Polish is the finish and quality of the facet surfaces, affecting the mirror-like quality of the diamond, and symmetry is the arrangement of the facets affecting whether a diamond will reflect light evenly from all areas of the stone. Poor symmetry will result in poor light performance. Polish and symmetry receive their own individual grade using the same scale as cut, excellent to poor. Only round brilliant cut diamonds receive a cut grade. All other fancy shapes, receive a polish and symmetry grade only.  

Colour

Diamond Colour Actually Means Lack of Colour

The colour of a diamond may be affected by chemical impurities and/or structural defects in the diamond when it is formed. Depending on the hue and intensity of colour, this can either detract from or enhance its value. For example, within the normal market range, diamonds with less colour are more desired and attract a higher value. Whereas, with fancy-coloured diamonds, such as red, pink, or blue the more intense the colour, the more dramatically the value can increase. 

Normal Market Range 

Around 98% of the world’s diamonds fall within the normal market range where a diamond is evaluated on the absence of colour. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water. It is generally more radiant and rarer and, consequently has a higher value.  

A diamond’s colour is graded by comparing a stone to a set of authenticated master diamonds under controlled lighting and precise viewing conditions by trained professionals. The Gemological Institute of America (GIA) colour scale is the industry standard for diamond grading. Their scale goes from D (colourless) all the way to Z (light yellow or brown in colour).  

Many of these diamond colour distinctions are so subtle that they are invisible to the untrained eye; the difference from one colour grade to another (for example, a G colour diamond and an H colour diamond) is very small. However, the difference between one color grade and another that’s three or four above or below it (for example, a E colour diamond and a H colour diamond) may be easy to see when the diamonds are side by side, especially under bright light and with magnification. 

Talking about Colour 

Colourless Diamonds (D, E and F) – D and E colored diamonds will display virtually no colour. They are icy white!  F coloured diamonds display a nearly undetected amount of colour, but only when viewed face down by a gemologist. 

While diamonds in this category will look beautiful in any colour metal, setting them in white gold or platinum will allow you to show them off to their fullest potential! 

Near Colourless Diamonds (G, H, and I) – Diamonds in this range appear colourless in the face-up position. However, when viewed face down, they exhibit a slight amount of body colour. In order to see the colour, the diamond has to be viewed against a perfect white background. 

Once the diamond is mounted on a ring setting, the colour is not usually detectable by a layman. Therefore, these diamonds can be the best option for getting the biggest bang for your buck! 

Faint Colour Diamonds (J, K, L, and M) – J to M graded diamonds will show some colour in the face-up position. However, some clients prefer this warmer look to the diamond especially if they are setting the diamond in yellow gold where the colour will be less noticeable. Depending on the circumstances, this option may provide real cost savings for a client who is budget minded and doesn’t want to compromise on size or clarity. 

Fancy Colour Diamonds 

Fancy colour diamonds are yellow and brown diamonds that exhibit colour beyond the Z range, or other coloured diamonds that exhibit colour face-up. These rarer specimens come in every colour of the spectrum, including blue, green, pink, and red. Coloured diamonds contain impurities or structural defects that cause the colouration, but unlike the normal market range where this detracts from the value, the scarcity of some of these colours mean they are highly desired and command high values. 

Fancy colour diamonds use a different colour scale from D – Z diamonds. It consists of a letter denoting the colour hue and a number that represents the intensity of colour. 

Pink Argyle Diamonds 

Argyle pink diamonds are iconic.  

Mined in the east Kimberley region of northern Western Australia, the Argyle mine has produced over 90% of the world’s pink and red diamond supply for over 3 decades, yet less than 1% of the mines total production is pink. Having exhausted its economic production, the mine was scheduled for (and ultimately) closed in November 2020 and without another significant source of these rare and highly sought-after diamonds, the values have risen sharply over the last few years. Red and Pink argyle diamonds, with tendered certification or Lot Numbers are often traded in the market as investment options.  

Clarity

Clarity characteristics come from events in the life of a diamond. Many are byproducts of the diamond crystal’s growth within the earth. Some can be caused during the diamond’s journey to the surface. The stresses of mining, processing, and cutting may create others. 

External characteristics are called blemishes. These are flaws on the surface of the diamond such as scratches. Some blemishes can weaken a diamond’s beauty and structure and can have a significant impact on value. Depending on the type of blemish it may not be visible to the naked eye. 

Internal characteristics are called inclusions and are only referred to as flaws as their presence means the diamond cannot be graded as flawless. Not many people can afford internally flawless diamonds, so inclusions are to be expected to some degree. 

Most inclusions present in gem-quality diamonds do not affect the diamonds’ performance or structural integrity and are not visible to the naked eyes. However, large clouds can affect a diamond’s ability to transmit and scatter light. Large cracks close to or breaking the surface of the diamond may reduce a diamond’s durability. Diamonds with higher clarity grades are more valued due to their rarity with less than 1% of the world’s natural diamonds being flawless. Clarity is an important factor when discussing a diamond’s beauty and value. 

Minor inclusions or blemishes can be useful, like a person’s individual features they make a diamond unique and identifiable. In addition, as synthetic diamond technology improves and distinguishing between natural and synthetic diamonds becomes more difficult, inclusions or blemishes can be used as proof of natural origin. 

Clarity Grading 

The Gemological Institute of America (GIA) developed the most widely used diamond clarity grade scale. These are the parameters they use. 

** A small percentage of SI diamonds have inclusions that can be seen without magnification. Some organisations grade these diamonds SI3 but GIA does not use that grade. 

To evaluate clarity, a skilled gemmologist examines the diamond under x10 magnification. Clarity characteristics are assessed on five standard criteria; Size, Number, Nature, Position and colour. 

Clarity Characteristics Under the Microscope 

Without advanced training it is very difficult to identify and name the different clarity characteristics you may see when viewing a diamond under 10x magnification. However, if the diamond has an Independent Diamond Certificate, the clarity characteristics may be listed on the certificate. Internal inclusions may be listed as either Crystals, Pinpoints, Clouds or Feathers. External Blemishes may be identified as Natural, Bearding, Extra Facets or in some instances there may be nicks, chips or scratches due to damage to the stone. 

Which Clarity Should I buy 

There is no right or wrong answer when choosing the clarity grade for your diamond. While some buyers may want a diamond as close to flawless as their budget will allow. Others are willing to compromise on clarity if other factors such as cut grade, colour or carat weight are more important. The most important factor is if you love the way the stone looks! It should first and foremost, catch your eye and attention. 

Carat

Diamond Carat Weight Measures a Diamond’s Apparent Size

Diamond carat weight is the measurement of how much a diamond weighs, not it’s visual size. After many attempts to standardise the weight of the Carat, the United States, United Kingdom and Europe adopted the use of the Metric Carat, which has become the standard unit of weight used throughout the diamond and gemstone industry today: 1 Carat = 0.2 Grams, although gram weight is rarely used when referring to diamonds.  

Carat weight is nearly always discussed in terms of points with 1 carat (abbreviated ct) being equal to 100 points (abbreviated pts). A diamond’s weight is usually written in decimal numbers. For example, a diamond that weighs exactly 1 carat is recorded as 1.00ct. Each one point of weight is shown as 0.01ct. This system allows diamonds to be accurately measured in weights that are either less or more than 1 carat. 

Diamonds are available in any subdivision of 100. While ½ (0.50ct),  ¾ (0.75ct) or 1 (1.00ct) carat diamonds are widely offered as engagement ring options, diamonds are available in any weight measurement, for example 0.38ct or 0.82ct. A diamond that weighs more than 1 carat will be represented as the whole number plus the subdivision to the next carat size. For example, 1.45ct or 2.69ct. 

Two diamonds that weigh the same may have different measurements. The carat weight is a guide only to the visual size of the stone. The actual dimensions are entirely dependent upon its proportions. On average, a well-proportioned 1 Carat round brilliant cut diamond has a diameter of approximately 6.4mm. In comparison, a shallow cut diamond of the same weight may be anything up to 20% larger in diameter, whereas a deep cut diamond of the same weight may be as much as 20% smaller in diameter. Neither of these variations will sparkle as much as a well proportioned diamond. 

Weight and value 

Consumers are used to buying products like meat, fruit, and vegetables by weight. Many precious commodities like gold and silver are also sold this way. Larger diamonds are found much less frequently in nature, so the price isn’t determined simply by weight. It depends on the rarity of the weight.  

A 100 gram bar of gold is no rarer than two 50 gram bars of gold, so it will cost no more per gram. In contrast, a 1 carat diamond is much rarer than two ½ carat diamonds of comparable quality. As a result, the larger diamond is more expensive than both smaller diamonds added together, assuming all other factors such as cut, proportion, colour and clarity are the same. 

Total Weight 

Total weight (sometimes shown as TDW) is the combined weight of all the diamonds in a piece of jewellery with more than one stone. Often this calculation is used when there are multiple stones and there is no specific value in outlining the individual weight of each stone.  

Choosing a Weight 

Many customers decide on the carat weight of the diamond they want to own before they ever try anything on. This might be based on information they’ve heard or read in various media sources or weights of diamonds owned by family members or people within their social circle. However, how the diamond looks on your hand and your overall budget are significant factors to consider. 

Budgeting Options 

If there’s a discrepancy between the carat weight you have chosen and the amount budgeted for the purchase, there are options to help solve this dilemma. 

Move down a weight category. For example, from 1 carat to 0.90ct. Both the per-carat price and the weight are less so the cost will be appreciably lower. Only an expert would notice any difference in appearance. 

Choose a design that combines several smaller stones rather than one larger stone. This can achieve a smaller price whilst maintaining a certain visual size on the hand. Halo, Trilogy and Cluster designs are popular options. 

Compromise on the other Cs, particularly clarity and colour. Slight differences in these are usually only apparent to trained professionals in controlled conditions or under loupe magnification, but there can be a significant impact on value.