The Guide To Diamonds 4Cs


Posted on January 08 2021

The Guide To Diamonds 4Cs

The Guide to the 4Cs of Diamonds

It’s not every day that you buy a diamond. Whether it’s for an engagement ring or a family heirloom, diamonds are always a special purchase. While we know diamonds for their sparkle, they are not all equal. The 4Cs–carat, colour, clarity and cut–determine the quality of a diamond. This article is your ultimate guide to the 4Cs of diamond quality, so you know exactly what to look for.

About the 4Cs

Diamonds are one in a million. They are one of the world’s most beautiful natural creations—and one of its most sought after.

Although the first diamond was found in the fourth century BC, it would take until the middle of the twentieth century for a standard to be agreed on diamond quality. The Gemological Institute of America–the GIA–are the brains behind the ‘4Cs’. The 4cs are now used to describe every diamond. Before the creation of the 4Cs, you had to depend on your eyesight and jeweller to tell you the quality of a diamond.

The 4Cs provide jewellers with a universal language by which to describe diamonds, making it easier for clients to understand exactly what they are buying. Each of the 4Cs will play a role in determining the appearance–and the price–of your diamond. Each client might prioritise a different aspect of the 4Cs, although the cut is often the most focused on, as this has the greatest impact on the appearance and brilliance of a diamond. Depending on the cut, a diamond under a carat compared to one over a carat and a half can appear equally beautiful. 

When choosing a diamond, you will want to find a balance between the 4Cs within your price range. If you prioritise carat size over the other 3 aspects, you could end up with a diamond that is lower in quality than a smaller carat size would have afforded you. 

You can submit your gem to the Gemological Institute of America for certification, which will give you an in-depth look at your diamond. It’s important to note that the 4Cs focus on natural diamonds, and there is some variant in grading for lab-grown diamonds.

When you understand how the 4Cs work, you can choose a visually pleasing diamond that can become an heirloom.

Diamond Carat

The first thing that you will notice about a diamond is its size. While you might think a ‘carat’ is the diamond’s size, it is the weight of the diamonds.

Jewellers weigh a diamond in carats, which is a very precise measurement. Each carat weighs 200 milligrams, allowing for tiny fractional carats. A carat can be split into 100 points, which can describe smaller diamonds. Each carat weighs about the same as a quarter of a raisin. You may see a diamond described as a ‘twenty-five pointer’ to reflect the fact that it is a quarter of a carat. Once you go above a full carat, we describe diamonds as their carat and decimal weight.

The weighing system for diamonds come from their origin as a carbon element. Traditionally, diamond traders would weigh their stones against carbon seeds on a set of scales to determine their weight. Unlike other measurement units, the carat system is the same around the world.

The carat of your diamond is a key indicator of the price, as larger diamonds are rarer and naturally come with a higher price tag. However, you can have two diamonds of equal carat at different prices depending on where they sit on the rest of the 4Cs. Some carat weighs are more desirable than others and can be referred to as magic sizes. You’ll typically find jewellery–particularly engagement rings–that is a half-carat, three-quarter carat or a full carat. 

While the carat is important, you can have two diamonds of the same carat that look different due to their cut. You’ll want to determine each of the 4Cs to purchase the most brilliant diamond within your price range.

Diamond Colour

Diamonds are a unique creation. While we tend to think of colours in shades of the rainbow, a diamond’s colour is determined by its lack of colour and whiteness. The purer the diamond, with no hue of colour, the higher its value.

The Gemological Institute of America, who came up with the 4Cs, has a four-letter grading system for diamond colours. A ‘D’ diamond is lacking any colour, while a ‘Z’ diamond has a strong hue of yellow or brown, which is noticeable. While you may not detect these hues with the naked eye at certain grades, each diamond is forensically examined to determine its colour.

The setting that you chose for a diamond will impact how colourless it appears to the untrained eye. A ‘D’ colour diamond will only be able to show off its brilliance if it is expertly cut to reflect the light.

You might expect the ‘colour’ in the 4Cs to revolve around gems such as a pink diamond. Instead, these diamonds are known as ‘fancy-colour diamonds’ by the GIA and have their own separate colour range to traditional diamonds.

Read more in details about Color .

Diamond Clarity

A diamond’s clarity is determined by its absence of any blemishes and inclusions. The process through which a diamond is made naturally results in these imperfections, as diamonds are formed when carbon is exposed to both heat and pressure under the earth’s surface.

We call the internals flaws in a diamond ‘inclusions’ while external features are known as ‘blemishes’. A diamond forms an inclusion when a group of small crystals are trapped within the diamond when it is being formed, which results in an irregularity in the atomic structure of the diamond.

Each diamond has its clarity rating, and there is a specific way of determining the grading of an inclusion or blemish. The number of flaws, their size, nature, and their position on the diamond will determine its overall appearance and where the diamond sits on the clarity scale. You will never find a pure diamond, even if it appears so to the naked eye and a magnifying glass.

The GIA has a clarity scale which has six categories and eleven specific grades. Similarly to the 4Cs, their clarity scale is universally applied. In order of most valuable, they are:

  • Flawless–FL–there are no inclusions or blemishes visible when the diamond is placed under 10x magnification. These are the rarest form of diamonds.
  • Internally Flawless–IF–no inclusions are visible when the diamond is placed under 10x magnification.
  • Very, Very Slightly Included–VVS1 and VVS2–the inclusions in the diamond are so slight that they are difficult for the grader to determine under 10x magnification. There are two grades in this category.
  • Very Slightly Included–VS1 and VS2 - inclusions can be seen when the diamond is under 10x magnification, although they are minor in characteristics. There are two grades in this category.
  • Slightly Included–SI1 and SI2–there are noticeable inclusions when the diamond is under 10x magnification. There are two grades in this category.
  • Included–I1, I2 and I3 - Inclusions are obvious when the diamond is placed under 10x magnification. This level of inclusion may impact the transparency and brilliance of the diamond. There are three grades in this category.

As these gradings are made when a diamond is under 10x magnification by a trained diamond grader, the naked eye will hardly notice the difference between most of these gradings. They play a major role in determining the quality and price of a diamond, with more flawless diamonds retailing for a premium price.

You will want to find a diamond with the highest clarity to your untrained eye that is within your budget. While most people won’t be able to spot inclusions in your diamond, they will see how it sparkles in the light.

Read more in details about Clarity

Diamond Cut

When you think of a diamond’s cut, the first thing that jumps to your mind are the shapes of diamonds, like the emerald cut, cushion cut and round diamonds. In reality, the cut of a diamond is more complicated than that.

Diamonds are a girl’s best friend because of how they catch the light and sparkle in the sun. The cut of a diamond, such as its proportions and symmetry, determines how it interacts with light.

The diamond’s cut is the most difficult of the 4Cs to determine. Features that determine the cut include a diamond’s:

  • Table size
  • Star length
  • Girdle thickness
  • Lower girdle/half facet length
  • Total depth
  • Crown height
  • Crown angle
  • Pavilion angle
  • Pavilion depth
  • Culet

Each of these facets makes up the cut of the diamond, and they play a unique role in determining how the diamond interacts with lights and the visual effects that it creates. The pavilion depth impacts the spectrum of light created as when the depth of the pavilion is too shallow, light can escape from the side and bottom of the diamond.

A well-designed diamond will have a facet arrangement that directs the light upward through the crown, particularly for diamond rings.

There are three common visual effects created when a diamond catches the light:

  • Brightness: white light is reflected internally and externally by the diamond.
  • Fire: white light is scattered around the diamond in all the colours of the rainbow.
  • Scintillation: the sparkle that is produced when a diamond catches the light and the pattern of both light and dark areas that result from the reflections.

As diamonds are polished and not sold in their rough form, their cut results from craftsmanship and design. The cut results from the design, the quality of polish in each facet of the diamond, the symmetry of the facets, the weight to diameter ratio and the thickness of the girdle. 

There are separate cut scales for each type of diamond, and the standard round brilliant diamond has a five-part grading system which ranges from excellent to poor, which is the definitive scale for diamond cut classification.

The overall GIA diamond cut grading does have a sixth option of an ideal cut, which is not included in the round diamond scale.

  • Ideal–is awarded depending on the shape of the diamond
  • Excellent 
  • Very Good
  • Good 
  • Fair
  • Poor

The cut of your diamond will significantly impact how it looks to the naked eye. You want a diamond that sparkles under the light, and sometimes even a higher carat diamond struggles if its cut grading is low. If you want to focus on one aspect of the 4Cs when choosing a diamond, it should be its cut.

Which of the 4Cs is most important?

All diamonds are not made equal. It’s important to consider which aspects of a diamond are worth spending more money on. Each element has its own grading system which determines its price, and each of the 4Cs come together to impact the overall quality of your diamond.

You want each of the 4Cs to work together to give you a diamond with that can become a family heirloom. 

You should start by focusing on the cut of your diamond, as this has the greatest impact on its visual beauty. Search for a diamond that has high brilliance and fire with an excellent cut and prioritise this over the colour or clarity of your diamond.

The second C that you’ll want to consider next is the colour. Think of your diamond is the sense of what the naked eye can see. You want your diamond to appear as colourless as possible, to give you the cleanest light reflection and sparkle.

For the clarity of your diamond, you want your gem to appear clean with no blemishes that are noticeably distracting to the exterior. While the carat of a diamond is often marketed as its major selling point, the other 3Cs will impact how your diamond looks more than its carat weight. 

By understanding the 4Cs and how they impact the finish of your diamond allows you to decide which aspects to focus on when searching for a piece of jewellery. Always keep in mind the 4Cs and how each determines the visual appearance of your diamond. 


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