The 4Cs of Diamonds

What are The 4Cs of Diamonds?

When it comes to buying a diamond, the 4Cs- cut, colour, clarity and carat weight- are your essential guide. Established by the Gemological Institute of America (GIA), these four key characteristics form the global standard for assessing a diamond’s quality and value. Whether you're choosing a diamond for an engagement ring or simply want to understand what makes one stone more valuable than another, learning the 4Cs will help you make confident and informed decisions.

Colour

The colour of a diamond refers to how much, or how little, colour is present within the stone. The GIA colour scale assesses diamonds in a range from D (colourless) to Z (light yellow or brown). The scale primarily focuses on the presence and intensity of yellow or brown hues in white diamonds, as these are the most common colour tints found in nature. This grading system primarily applies to colourless diamonds, not to fancy-coloured stones like pink, blue, or yellow diamonds, which are valued differently.

Clarity

Diamonds formed deep within the earth under intense pressure and heat often contain unique imperfections. These can manifest as inclusions, internal flaws such as crystals, feathers, or tiny mineral deposits, and blemishes, or external flaws like scratches or chips. Clarity grading evaluates the presence, size, location, and visibility of these imperfections.

Diamond clarity is assessed using a standardised grading scale established by the Gemological Institute of America (GIA) and widely adopted by the industry. The scale ranges from Flawless (FL) to Included (I3), with several clarity grades in between.

Carat

Carat refers to the weight of a diamond. A single diamond carat is equivalent to 0.2 grams, approximately the weight of a paper clip. The term "carat" comes from the carob seed, historically used by gem merchants for its uniform weight.

While carat is often linked to size, the cut of a diamond can significantly affect its perceived size. A well-cut smaller diamond may appear larger than a poorly cut one with a higher carat weight. Carat weight also impacts a diamond's value, but two diamonds of the same size can have different values based on their cut, clarity, and color. The point system is used to express finer carat weights, such as 50 points for 0.5 carats. Ultimately, selecting the right carat weight is a matter of personal preference and how it fits your style.

Cut

The cut of a diamond refers to how its facets are arranged to interact with light, influencing its brilliance and sparkle. It's different from shape (like round, oval or pear), which describes the diamond's outline. When cut properly, light enters the diamond's table, reflects internally, and exits through the top, creating the sparkle diamonds are known for.

Diamonds are typically cut in one of three styles: brilliant (triangular and kite-shaped facets), step (rectangular facets), or mixed (a combination of both). Cut is graded based on appearance, balance, symmetry, polish, and durability. Only round brilliant diamonds receive a formal cut grade, ranging from Excellent to Poor, due to their standardised facet arrangement. Other shapes, like pear or marquise, don’t have formal cut grades due to their varied facets.

While modern cutting maximises light performance, antique old-cut diamonds have a softer glow and unique charm. Shaped by hand, they have chunkier facets and a distinctive sparkle, offering a more individual and historical appeal that modern cuts can’t replicate.