Understanding the 4Cs Used for Evaluating Diamonds Will Empower You to Find the Right Diamond

Understanding the 4Cs Used for Evaluating Diamonds Will Empower You to Find the Right Diamond

The process of selecting a diamond for a ring or adornment on a piece of diamond jewellery has a lot more dimensions to it than you might expect. For new diamond buyers, it is important to be familiar with each of the qualities on which a diamond is graded. Colloquially, these qualities are known as the 4Cs. They are:


Cut: How light interacts with the facets of a diamond, determined by its symmetry, proportions, and finish

Colour: The natural tint of a diamond, with colourless being the most valuable

Clarity: How pure or free of inclusions and blemishes a diamond is

Carat: The weight of a diamond


A diamond’s overall quality and price are determined by a combination of these factors, as they are the defining features of a diamond. Becoming familiar with each of these grading qualities will help you ascertain which diamond is right for you. For example, a stone used in diamond earrings may not need to be as high quality as one in a diamond necklace, though these decisions are entirely down to your personal preference. 

The 4Cs are a grading system invented by the Gemological Institute of America (GIA), the world’s leading research and educational institution for gemology. MarryMeDiamonds references the GIA’s grading system for each of the 4Cs and includes a GIA certificate for all diamonds exceeding .30 Carat.



One of the most illustrious features of a diamond is the unmatched sparkle and shine that appears when light reflects off the diamond’s surface. No other precious gem in the world can replicate the distinctive shimmer of a diamond. How light interacts with a diamond is a result of its Cut. 

Contrary to popular belief, a diamond’s Cut does not equate to its shape. Shape refers to the external form of a diamond, whereas Cut refers to the symmetry and proportions of the angles on its faces, as these more significantly affect how light interacts with the diamond. This makes Cut the most important aspect of a diamond’s overall appearance. The most popular Cut for a diamond engagement ring is the Round Brilliant.

The GIA grades a diamond’s Cut against three factors: Brightness, Fire, and Scintillation. Brightness refers to the internal and external white light caused by light reflecting off a diamond; Fire denotes the spectrum of light caused by reflection; Scintillation refers to how much sparkle the diamond emits.  

From these grading criteria, each diamond’s Cut is then graded on an overall scale ranging from Excellent to Poor, as laid out by the GIA.



Like all gemstones, diamonds are formed with varying colours. The purest and highest-rated diamonds do not have any colour or hue, excluding fancy-coloured diamonds such as the pink diamond. Having no colour means that a diamond is chemically and structurally perfect and is therefore more valuable. 

The GIA grades diamond Colour on a scale from D to Z, with D being the purest and colourless, and Z being tinted with a yellowish hue. There are no diamonds with Colour grades A, B, or C, as the GIA created a more comprehensive grading system that replaced an antiquated system which used only those three grades.



A diamond’s clarity refers to how flawless it is, or how many or few inclusions and blemishes it has. These flaws are known as “characteristics”. Since diamonds are formed underground under intense pressure, it is natural that the vast majority of diamonds are unearthed with inclusions (internal characteristics) and blemishes (external characteristics). 

The GIA grades Clarity using six categories: Flawless (F), Internally Flawless (IF), Very, Very Slightly Included (VVS), Very Slightly Included (VS), Slightly Included (SI), and Included (I). Within these categories, there are subcategories, such as VS1 and VS2, totalling 11 different possible grades.

To the untrained eye, most inclusions and blemishes go unnoticed; however, they play a large role in determining a diamond’s value. This is one of the many reasons MarryMeDiamonds ensures that all diamonds over .30 Carat come with official grades from the GIA.



Simply put, Carat refers to a diamond’s weight, not its size. Carat is the most objective quality of a diamond since it is measured empirically, and thus has the biggest effect on a diamond’s price. The reason there is no direct correlation between price and Carat is because high-Carat diamonds need to be cut from a large raw diamond, which is harder to find naturally, whereas multiple low-Carat diamonds can be made from a single stone.

That said, Carat is not the most important aspect in determining how large a diamond appears. A diamond’s cut has just as big of an impact on how “big” it looks on a diamond ring or bracelet due to how light interacts with the diamond.

If you are looking for jewellery that includes multiple diamonds, such as a diamond necklace, ask the jeweller for information about each diamond’s Carat as well as the Carat Total Weight (CTTW) . 

Ultimately, buying a diamond comes down to budget and personal preference. Understanding the different aspects of the 4Cs will help buyers find the right diamond for them. It is best to consider which of the 4Cs are most important and work with a trusted jeweller to locate the right diamond for you.

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