Choosing a well-cut diamond is extremely important and for some it is the most crucial of the 4Cs.

The cut determines the sparkle that the diamond gives off. It contributes to the fire (colourful flares), brightness (light reflecting off the top) and scintillation (flashes of light).

The GIA developed cut grades to evaluate colour and clarity but also the structure of a diamond. An Ideal cut diamond will have many more facets than a poorly cut diamond and will also have close to the ideal diamond proportions to maximise light performance. This is about finding the right relationship between the width of the top (surface table) and the depth of the diamond. A diamond that is too deep or too shallow will allow light to leak through rather than be reflected back out.

Cut grading only applies to round diamonds as these are simpler to measure in terms of light performance. The scale consists of Ideal/Excellent, Very Good, Good, Fair and Poor. Use our diamond comparison tool to get an idea for how price changes with cut grade.

We recommend choosing an Excellent or Very Good to avoid a diamond that loses light and does not maximise its sparkle, giving a dull glass-like appearance. However, if you are aiming to stick to a lower budget, a Good cut offers great value. This cut is in the top 25% in the world.

Always bear in mind the importance of cut when considering a trade-off between the other Cs as light performance is very critical.

Feel free to get in touch for help with cut choice at

Excellent Cut Diamonds 

Also known as Ideal Cut they have been proportioned in such a way so as to maximize the light refraction potential thereby providing that fiery sparkle that sets these stones out from the rest.

Good Cut Diamonds 

The cut and shape of these diamonds allows a good amount of light to travel back out from the upper surfaces of the stone thereby still providing scintillation and sparkle but not as much as an excellent or very good cut diamond.

Fair Cut Diamonds

With a fair cut diamond most of the light is lost to the sides and does not refract back out through the uppermost surfaces. These stones re generally quite thick and deep and hence have e smaller table as compared with good or better cut stones .

Poor Cut diamonds 

Whilst a diamonds may have a very good colour and clarity a lot of the sparkle will be lost if the light cannot refract back out of the top surface of the diamond due to a thick or deep cut .In this case most of the light will be lost from the bottom of the stone.