Types of Diamonds Explained: The Four Cs

Buying an engagement ring can be very confusing, the majority of people will only ever do this once and it isn’t something you would want to rush in to. Using just a few snippets of knowledge can get you a long way and help you to understand exactly what it is that you are paying for. There's a vast range to think about when it comes to the different types of diamonds available - with the four Cs being considered in almost every diamond ring purchase. But what exactly do the four Cs mean and how do they make each diamond ring different. In this guide, we'll delve into the types of diamonds and their cut, colour, clarity and carat.

What is ‘Carat Weight’ and why does it sometimes say approximately?

When measuring/weighing gemstones we use carat weight, just as when weighing yourself you would use kilograms. Carat refers to the weight and therefore the size of the diamond. One carat is divided into 100 points. Therefore, a diamond weighing 50 points is half a carat. Size is the most obvious factor in determining the value of a diamond.  But two diamonds of equal size can have very different values, depending on their cut, clarity and colour.

Sometimes if the diamond is already mounted then a gemologist will take a few measurements then use a complicated mathematical formula to estimate the weight. This gives you an approximate figure e.g. 1.00ct approx.

Why when describing diamond colour does it say a letter and not just a colour?

Diamonds come in a large variety of colours, the most popular being clear/white. Instead of using terms like very very white, very white and white gemmologists decided to use the alphabet as a scale. Colour grade ‘D’ is the best with each subsequent letter the colour is slightly worse. That said, to the untrained eye and without holding two diamonds side by side Colour ‘D’ all the way to ‘J’ could look the same in non-lab conditions. ‘K’ onwards you start to see a yellow tinge which becomes more and more prominent along the scale. The more desirable diamonds are graded ‘D’ to ‘I’ and therefore cost more.

Clarity, What is it and why do I need to know?

To make things clearer for consumers gemmologists have developed a way to describe if a diamond is as clear as day or as dull as a duck pond.

FL/IF Flawless

FL/IF = Flawless, To buy a flawless diamond you need to have very deep pockets. This is a stone with no visible imperfections. Just take into account the size of the diamond you are purchasing, would you really be able to see any flaws anyway if the diamond is only 0.15ct ? (I couldn’t!!)

VVS1/VVS2

VVS1/VVS2 = Very Very Small inclusions, for a stone to be graded VVS1/VVS2 a trained gemmologist must inspect a stone through an eyeglass for a number of minutes in order to see any imperfections such as a minuscule clear bubble. Will you be doing this? If not then it is likely you can purchase a lower clarity of diamond without knowing the difference.

VS1/VS2

VS1/VS2= Very Small inclusions, minute specs that may be visible to a trained professional when looking through an eye glass, the diamond could be perfect but for a couple of tiny specs of what look like dust inside the diamond. VS1/VS2 clarity diamond aren’t cheap, but they do look very good.

SI1/SI2

SI1/SI2 = Small Inclusions, This is where ‘normal’ people might start to see the inclusions, still with the aid of an eye glass but much easier to spot. SI1/SI2 clarity stones are more common and therefore you can get more bang for your buck.

P1/P2

P1/P2/P3 = These inclusion could be seen without the need of an eye glass. they could consist of what looks like grit in the stone or make the stone look cloudy. 

The Cut of a Diamond

Cut is the only diamond characteristic directly influenced by man – the other three are dictated by nature. A good round brilliant cut releases the life, fire and sparkle of a diamond through the arrangement and proportions of its 57 to 58 facets (tiny planes that create angles to reflect light).  When a diamond is cut the light will reflect from one facet to another and disperse through the top of the stone, resulting in a display of brilliance and fire. Diamonds that are cut to deep or shallow lose light that spills through the side or bottom.

The Shape of the diamond is a matter of personal taste, here are the most common:

Round Brilliant

The round brilliant cut is the most popular diamond shape, prized for its exceptional sparkle and light performance. With 58 facets precisely angled to maximise brilliance, this cut reflects light beautifully from every angle, creating the distinctive sparkle that diamonds are renowned for. The round brilliant cut suits a wide range of settings and complements virtually any jewellery design. It performs well across all clarity and colour grades, though higher grades will naturally display greater transparency and radiance. Its timeless, versatile appeal makes it the preferred choice for engagement rings and classic fine jewellery pieces.

Princess Cut

Princess cut diamonds are a modern classic, featuring a square or slightly rectangular shape with sharp, uncut corners and brilliant faceting. This contemporary design maximises sparkle and light return, making princess cuts exceptionally bright and fiery. The geometric precision of the cut creates a sophisticated, architectural appearance that suits both traditional and contemporary settings. Princess cuts typically require a slightly higher carat weight to appear as large as round brilliants, but their distinctive angular elegance and exceptional brilliance make them a popular choice for engagement rings and fine jewellery pieces.

Marquise

A marquise cut diamond features an elongated, boat-shaped silhouette with pointed ends and curved sides. This distinctive cut maximises the stone's surface area, making it appear larger than other cuts of similar carat weight. The marquise shape creates a flattering, slenderising effect when worn in rings. With 58 facets, it offers excellent brilliance and sparkle, though the pointed ends require careful setting to protect them from chipping. The cut works particularly well for solitaire settings and complements both classic and contemporary designs.

Emerald Cut

The emerald cut is a rectangular diamond shape with step facets that create a distinctive hall-of-mirrors effect. Known for its elegant, vintage appeal, this cut emphasises clarity and colour over sparkle, making it ideal for showcasing high-quality stones. The emerald cut requires excellent clarity grades because inclusions are more visible in this facet pattern than in brilliant cuts. Its elongated proportions create a sophisticated, timeless look favoured by those seeking understated luxury and distinctive character.

Pear Cut

Pear cut diamonds combine the elegance of a round brilliant with the elongated sophistication of a marquise. This distinctive teardrop shape features a rounded end on one side and a pointed tip on the other, creating a flattering silhouette that appears larger than diamonds of comparable carat weight. Pear cuts work beautifully in solitaire settings and are particularly striking when paired with side stones that complement the shape's natural flow.

Oval

An oval cut diamond features an elongated, symmetrical shape with rounded ends and curved sides that create a graceful, elongated silhouette. This versatile cut maximises the stone's surface area, making it appear larger than other cuts of similar carat weight. The oval shape offers a flattering, slenderising effect when worn in rings and works beautifully in both solitaire and halo settings. With 56 to 58 facets, it delivers excellent brilliance and sparkle comparable to round brilliant diamonds. The oval cut complements both classic and contemporary designs, making it a popular choice for those seeking a distinctive yet timeless appearance.