Depth of a diamond and how to choose your diamond ring

Depth of a diamond and how to choose your diamond ring

It is important to understand why each part of a diamond has been made in a particular way in order to achieve the sublime, the perfect round brilliant cut diamond, with hearts & arrows and all.

Diamonds have been studied for a very long time by gemologists and cutters in order to achieve the most perfect cut, the one that would reflect the best in every diamond. There are many aspects that had to be taken into account and one of these is the depth of a diamond.

Depth of a diamond

In this article we would like to share with you details regarding the ideal depth of a diamond and what to look for when purchasing a diamond ring.

The depth of a diamond is measured two ways: a. in millimetres, from the table to the cult and b. the depth percentage in relation to its width.

It is important to note that the ideal depth in a diamond is not the same for all shapes, it can vary considerably whether you are looking at a round brilliant or a princess cut for example. We will be discussing here the depth for a round stone.

Ideal dimensions and why

According to the GIA, a well proportioned diamond should have a total depth percentage around 60%, ideally between 57.5% and 63%. That is when it would be graded “Excellent” for the total depth.

Why is that? For several reasons: first of all, if the diamond is cut too deep, the light leaks out the diamond instead of being reflected back which causes it to look darker and more dull, this optical phenomenon is called “nailhead”.

On the contrary, should the diamond be too shallow, the girdle is actually reflected in the diamond and it causes the optical phenomenon called “fisheye”.

Obviously, even if a diamonds depth is excellent, if its table percentage and the angles are poor, the overall look of a diamond will be far from perfect. They all play an important role when looking at purchasing a diamond ring, to ensure it displays the most fire, brilliance and scintillation which are the dominant features of diamond.

The GIA’s cut grading system goes from excellent, very good, good, fair to poor.

Purchasing the right diamond ring

You now have a little more knowledge regarding what to look for in terms of depth in a diamond. Of course, the cut grades and numbers are not set in stone and should you fall in love with a diamond ring, which may officially display a good or very good cut grade, you need to follow your heart and not hesitate!

At BAUNAT we offer various grades of diamond cuts to satisfy all wishes. From the triple excellent grade by the GIA and less, to other certifications by other reputed labs such as HRD.


It is important to BAUNAT that you are well informed, we would therefore be delighted to help you with your queries and your search anytime. Don’t hesitate to contact us, we are happy to assist you by phone, email, chat or in person.

Author: Naomi Howard

Inspirational insights