The Basics of round brilliant cut diamond

Elegant, classic and astounding! This Cut is the most popular diamond shape and makes up the vast majority of diamonds found in engagement rings. Setting standards for other diamond cuts, the classic round brilliant cut diamonds account for over 75% of diamonds sold today. If you are looking for a shape that displays striking fire and a high degree of brilliance, this may be your perfect style diamond cut.

A round brilliant cut diamond is comprised of 58 individual facets (flat, geometric shapes). This only differs when there is a culet (point) integrated into the design, of which there would be 57 facets instead. The cut is made famous for its unique length and width ratio, which is 1.00 - 1.02 respectively. The most brilliant diamonds of this type adhere to a stricter measurement, of which is 1.00 to 1.01.

These measurements are an important clue as to the popularity of the round cut. Each facet is designed to reflect maximum fire and shine throughout the diamond. This provides the rainbow effect that you see when looking into a diamond, acting in the same manner as a prism would. The angle of the crown of the diamond is preferred to be 34° to 34.9°. Due to its famed brilliance, the round cut is often the most common image of a diamond in popular culture.

The Anatomy 

The History 

The round cut, as we know it today, is a direct evolution from the old Mazarin cuts of the 17th century. However, its origins can be traced right back to the very first point cuts that emerged in Europe in the 14th century. The point cut was a source of great interest and research for gemmologists and scientists alike, and this fascination has followed the past of the round cut ever since. No other diamond cut has received as much attention as the round shape.

The round cut underwent an unprecedented level of research and scrutiny during the 17th and 18th centuries. Amazed at its prism-like properties, scientists and gemmologists alike analysed the fire and brilliance that made these cuts so desirable. As a result, the very shape of the round cut changed considerably during a short space of time. This eventually lead to the development of the Brilliant Mazarin, as well as the famed Peruzzi cuts of the early 1800’s.

Its popularity can be traced back to the publishing of a book called “Diamond Design”, authored by Marcel Tolkowsky - a Polish diamond cutter. Marcel, who is attributed as being the father of the modern-day brilliant round cut, researched the geometrical and mathematical aspects behind the cut itself. In his book, he listed out detailed criteria behind the makeup of a brilliant cut. These criteria are still used today, and are known as either the “American Standard”, or the “Tolkowsky Standard”.

Browse our collection of round solitaire diamond engagement rings.