This site has limited support for your browser. We recommend switching to Edge, Chrome, Safari, or Firefox.
Understanding the 4Cs diamond grading scale - Lelya

Understanding the 4Cs diamond grading scale

When shopping for a brilliant cut, white diamond, it’s important to be familiar with the Four C’s: Cut, Clarity, Carat, and Colour – a universal language that was established by the Gemological Institute of America (GIA) and is followed by leading global gemological institutions such as the GIA or the IGI (International Gemological Institute). Th 4Cs are the primary factors that determine a diamond’s quality, value, and overall appearance.

Here’s what you need to know about each one

  • Cut refers to the diamond’s proportions, symmetry, and polish, which influence how well it reflects light. A well-cut diamond will have maximum brilliance, sparkle, and fire, while a poorly cut diamond will appear dull and lifeless. The cut scale is as follows: excellent, very good, good, fair poor.
  • Clarity refers to the presence of inclusions (internal flaws) and blemishes (external flaws) in the diamond. The clearer the diamond, the rarer and more valuable it is. A diamond with few or no inclusions is considered flawless, while one with many inclusions is considered included.
GIA Clarity Scale
  • Carat weight is the measure of a diamond’s size and is the simplest of the Four C’s to understand. A carat is equivalent to 200 milligrams and is divided into 100 points. So, for example, a 50-point diamond is equivalent to 0.50 carats. There are 5 carats in 1 gram.
  • Colour refers to the hue, tone, and saturation of a diamond. The most prized mined diamonds are completely colourless, with no hue or tint. The Gemological Institute of America (GIA) uses a scale from D (totally colourless) to Z (light yellow or brown) to grade a diamond’s colour.
Gia Colour Scale

When shopping for a diamond, it’s important to keep in mind that the Four C’s are interrelated, and the value of a diamond is a result of the balance between all four factors as well as other factors. A diamond with high carat weight but poor clarity, for example, may not be as valuable as a diamond with lower carat weight but excellent cut, clarity, and colour.

Other important characteristics to keep in mind

Some other characteristics, beyond the 4Cs that influence the quality and the price of a diamond but are rarely mentioned are symmetry, ratios, polish, location/type of inclusions, and fluorescence.

Taking location of the inclusions as an example – a diamond that ranks higher on Clarity scale that has an inclusion in the centre compared to a diamond that ranks lower on Clarity might be less expensive and have worse appearance to the viewer. Side inclusions can be eliminated by placing them under prongs (the pieces of metal that hold diamonds in place) making the stone appear flawless. A centrally placed inclusion is there to stay.

While round diamonds tend to have similar proportions, fancy cut diamonds such as ovals or marquise cuts have varying ratios. This means that while the carat weight might be the same, one stone could be flatter (appearing larger when looked at from above) and another one could be deeper (smaller when looked at from above). This is why it is important to seek professional advice and rely on your jeweller’s experience rather than relying purely on the 4Cs characteristics.

The same scales apply to mined diamonds and lab grown diamonds however it is worth noting that on average, lab grown diamonds are created to the top end of the quality ranges. At Lelya, all lab grown diamonds used in our designs are colourless, eye-clean with excellent cut, polish and symmetry guaranteeing maximum brilliance and sparkle.



Ultimately, the Four C’s are a useful tool for understanding the quality and value of a diamond, but they are just one factor to consider. It’s also important to consider the diamond’s overall appearance and whether it meets your personal preferences and needs.

By understanding the Four C’s, you’ll be better equipped to make an informed decision when shopping for a diamond engagement ring. Remember to keep in mind that the value of a diamond is a result of the balance between all four factors, and don’t hesitate to seek advice from our experienced team.

To get in touch, email us at

Photo courtesy of Misfit Diamonds

Use coupon code LEUK2024 for 10% off your first order.


Congratulations! Your order qualifies for free shipping You are £0 away from free shipping.
No more products available for purchase