The Cut of A Diamond

The Cut Of A Diamond

I met a client last week who was comparing two diamond rings he was considering. He produced a note a jeweller had scribbled the diamond details on, it stated: F colour, Si 1.23ct. That was it.

I explained it was difficult to give him an opinion on whether the ring he had seen was good value for money or not. 

Then today, I started to write a blog post about "cut" as there are so many misconceptions about what it refers to, and as I began drafting my post, I realised that this is a perfect example of why I could not price compare or quality compare the diamond ring for my chap from last week.

There are many factors involved when choosing a diamond - you have probably already heard of the four C's and it is likely you could name all four, or have a good go at it anyway, and the jeweller who wrote down the colour, carat and clarity grade of the ring last week clearly thought the information would be useful. But, there are so many more factors to consider when buying a diamond and even the small word "cut" refers to a myriad of different elements.

So, did you know that the "cut" of a diamond refers to its symmetry, polish and proportions and not just its shape? The term "cut" is often confused for the shape of a diamond, whereas it actually refers to how well the diamond has been cut and assesses the things that have a huge impact on the sparkle-factor of the diamond. Now, I could get all technical and start talking about percentages, but that would be quite dull, so instead I will throw in a few diagrams that help demonstrate how important the cut is.


The distance from the bottom of the girdle to the cutlet is called the Pavilion. A diamond with either a shallow or deep pavilion will struggle to produce exceptional sparkle as the light will either escape out the side or leak out the bottom of the diamond, as demonstrated beautifully by this little diagram:

But, it is not just the pavilion that is important when it comes to "cut". If the diamond has poor symmetry, then that also affects the refraction of light and ultimately the brilliance and sparkle of the diamond.

diamond symmetry

These are all the things a good jeweller will be looking at when assessing or choosing a diamond for you. Balance, symmetry, polish, facets...they are all important in their own, unique way to the overall impact and beauty of a diamond. They all have a direct relationship with how the diamond interacts with light and therefore, the diamond's resulting brilliance, fire and scintillation. And that is even before we start thinking about the other three C's!

So, when I am asked to give an opinion on another ring, without seeing it, I actually find it impossible. A diamond that is F in colour, Si in clarity and weighs 1.23ct could be hugely different from a diamond with the exact same colour, clarity and carat. The two may differ vastly in their symmetry and proportions. One may be worth a lot more money than the other. One may have brilliant sparkle, whilst the other may be lifeless and this can all be down to the diamond's proportions and symmetry.

Diamonds are, I suppose, like people. Two people may weigh the same, have the same coloured hair and eyes and be the same height, but each person's personality and nature shines out of them differently. Only you will know what is important to you once you begin your diamond search. Just as you naturally warm to some people and not others, you will also warm to your perfect diamond.