The Round Brilliant Cut is arguably the most popular and most recognizable diamond cut of all the cuts available with over 75% of all diamonds used in jewelry cut to this shape, this is because it achieves the greatest brilliance and fire. This cut is certainly the most popular amongst buyers at the present time with the Princess Cut being a distant second.

The current Round Brilliant Cut was developed from the Old European Cut from the 19th Century. It was previously introduced in the 17th Century, known as Mazarins or Double Cuts: had 17 facets (making it pretty dull compared to today's cut, which has 58 facets). From this the facet count was increased to 33 by Vincent Peruzzi, this cut was now known as the Peruzzi Brilliant or the Triple Cut. By the 19th Century the Old European Cut had become the most popular cut: with a shallower pavilion, a more rounded shape and different arrangement of facets. Marcel Tolkowsky, a Russian mathematical genius, then calculated the cuts necessary to create the ideal Diamond shape. Since this, there have been minor developments due to Tolkowsky not being completely perfect - he hadn’t followed the path of light rays that were reflected more than twice inside the diamonds, making his results incomplete. 


These proportions for the perfectionist in terms of the Round Brilliant Cut are a depth percentage of between 59.3% and 62% and a table percentage of 55% to 58% this would help to maximize the brilliance and scintillation as the gem appears to dance and sparkle in the light. Diamonds of such quality are hard to come by as there is such a huge demand for these.


The Round Brilliant diamond in its ideal proportions is designed to give maximum scintillation, beauty and fire. Round diamonds make up the vast amount of diamonds found in engagement rings and are popular in stud earrings and pendants. The Brilliant cut follows more naturally the rough diamond crystal shape, and is therefore the most popular for cutting due to the beauty it returns. It has the appearance of being larger than it actually is, meaning a higher carat weight is not essential when purchasing the gem. The hearts and arrows phenomenon which can be seen in Round Brilliant Cut also are attractive selling points: this is seen when the top or table facet is exactly perpendicular to the bottom or pavilion of the diamond.

Technical Specifications

  • The Round Brilliant diamond shape has 58 facets (including the culet) comprising 33 facets on the crown and 25 on the pavilion.
  • The crown facets comprise the table, 8 star facets, 8 kite facets, and 16 upper girdle facets.
  • The pavilion facets comprise 16 lower girdle facets and 8 pavilion main facets. There may also be a culet.
  • For a diamond that’s a perfect circle, look for a stone with a ratio of as close to 1.00 as possible.