Fine Jewelry

How to spot a real diamond and decode the four Cs

The technical jargon surrounding diamonds can be off-putting. So, to demystify the craft, CHARLIE BOYD decodes the four Cs and fine jewelry terms that matter to ensure you select a sensational, sustainably sourced jewel that speaks to you

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When buying a piece of diamond jewelry, the technical specifics can feel like another language; however, it’s easy to decode gemstone certificates when you know how. Diamond certification explains the technical grading of a stone in relation to certain qualities, carried out by a recognized regulatory body such as the Gemological Institute of America. Once you know how to evaluate these key qualities, it becomes easier to select which stone appeals to you most – and you will understand its unique beauty as well as its value on paper. Let our diamond directory explain the jargon that will ensure you select a sensational stone.


The most highly prized and valuable diamonds appear as close to colorless as possible, as if exuding bright-white fire. Graded on a sliding scale from D (the purest shade of white) to Z, most diamonds that appear white to the naked eye range somewhere between D and J. The larger the stone, the easier it is to notice the nuances of its color, and the metal choice (whether white gold or yellow gold) can also influence the overall brightness of the diamond once it is set in a piece of jewelry. But a diamond’s color is the most obvious telltale sign of its certification without inspecting it with a loupe (a jeweler’s magnifying glass). “Color is a very personal and subjective preference,” explains Emily Wansbrough, fine jewelry and fine watches buyer at NET-A-PORTER. “Some customers admire the purest white diamonds, while others prefer those that display a slightly warmer hue, with a slight champagne tint.”

Colored diamonds, however, are graded on a different scale entirely, with their intensity of hue indicated by terms such as Fancy, Fancy Intense and Fancy Vivid. Diamonds can come in shades of blue, pink, yellow, green, orange, brown, red and black; those with paler hues tend to be less expensive, while Fancy Vivid diamonds are exceptionally rare and highly prized. In the past couple of decades, the price of colored diamonds has skyrocketed due to their extreme scarcity. Celebrities such as Jennifer Lopez, Blake Lively and Lady Gaga have fueled the desire for pink diamonds, while Olivia Palermo, Heidi Klum and Victoria Beckham have all worn canary-yellow stones.


The cut of a diamond, in simple terms, is its shape. When choosing a diamond cut, most people make a selection based on the overall silhouette they admire, rather than the quality of the cut itself, which can be evaluated by a gemstone expert for its symmetry and precise craftsmanship. It is helpful to think of each cut as a rudimentary shape, like a preschooler might learn with wooden blocks. Cuts such as round brilliant, heart shape, oval and pear shape are pretty self-explanatory. Yet others, such as marquise (an oval with pointed ends), emerald cut (a rectangle), Asscher (a square) and cushion (a square with rounded corners) are more technical to get to grips with, and their structural differences are extremely complex. That said, you can still learn to identify their overall silhouette easily and quickly. “Those only concerned with the silhouette of their stone should seek examples that look well-proportioned and symmetrical,” explains Wansbrough. “A pear-shape diamond that is too slender isn’t as highly prized as one with a full-bodied belly that peaks to a perfect point.”


The clarity of a diamond denotes the number, size, position and color of its natural inclusions and blemishes – small imperfections that sit within its depths or upon its surface. ‘Flawless’ is the ultimate accolade, meaning the stone has no flaws visible under x 10 magnification. The scale then descends to include Internally Flawless, VVS1 and VVS2, VS1 and VS2, SI1 and SI2, and culminates with Included, with decreasing numbers of visible flaws under magnification at each grade. While this may sound confusing, when we remember how diamonds are formed, the varying qualities make a lot of sense. Natural diamonds occur when carbon is exposed to intense heat and pressure deep within the earth, and, inevitably, these stones contain individual characteristics – some of which are more obvious than others. “No diamond is entirely pure, but the closer it comes to purity, the more valuable it is,” explains Wansbrough.


Carat is the unit of measurement used to describe a diamond’s weight, with one carat equal to 0.2 grams. The ratio of weight and dimension, however, can have a striking effect on the overall visual size of a stone. A round diamond that is two carats but is very wide and flat, for example, may well look larger than another diamond of the same weight that has a deeper silhouette. “As with color, the importance of carat weight can be subjective to each individual. Some may prefer to have a round stone that looks smaller but has more balanced proportions, while others will look for a shallower stone that appears larger on the finger,” says Wansbrough.

Ethical origin

Diamonds have a muddied history where ethical values are concerned, but in recent decades, significant measures have been introduced to reduce negative impact on the environment and those involved in the mining process. All of NET-A-PORTER’s jewelry designers adhere to the Kimberley Process Certification Scheme, which was introduced in 2003 to prevent ‘conflict diamonds’ entering the mainstream diamond market. “This is something we take very seriously when looking at brands to launch on NET-A-PORTER,” says Wansbrough. “Where our brands source their diamonds and how they go about it is of paramount importance.” Complying with the Kimberley Process, each stone is guaranteed to have been purchased from a legitimate source not involved in funding conflict and in compliance with United Nations resolutions. As a member of the Responsible Jewellery Council, NET-A-PORTER has also committed to advance ethical, social and environmentally responsible practices that respect human rights throughout the supply chain – from mine to retail – for all diamonds, colored gemstones, gold, silver and platinum metals used to create fine jewelry and watches. “Our designers take great pride in ensuring that their diamonds are ethically sourced,” adds Wansbrough. “Many of our designers are already members of the Responsible Jewellery Council themselves and use rigorously sourced stones for all their jewels.”

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The most important element of ensuring authenticity when purchasing diamonds is to shop with a trusted retailer. As the diamond industry has evolved, various technologies have allowed for other materials to draw ever closer to the appearance of natural diamonds. Cubic zirconia, white topaz, white sapphire, spinel, quartz or moissanite are all colorless stones that can emulate the appearance of a diamond, which many gem experts can identify with their naked eye (and some from across a dinner table) – but it’s much more difficult to do if you don’t know what you’re looking for. There are at-home tests that can give you an indication as to whether a stone is a real diamond or not, including holding it within a candle flame before submerging it in cold water to see if it shatters, or checking with a loupe for telltale bubbles within the stone. However, these are not always reliable methods, and many will damage or destroy a replica. Diamonds boast a unique sparkle factor – a combination of bright-white flashes, dark fire and rainbow hues that become easy to recognize over time – but the only reliable way to be sure is to take it to a jeweler for thermal and conductivity tests. Diamonds also tend to be set in precious metals, such as gold and platinum, so if your jewelry bears a silver ‘925’ hallmark, then you may wish to investigate further.