Brilliant Cut Diamonds

The brilliant cut diamond is the most popular of all the diamond cuts. Specifically designed for the optimum display of brilliance, fire and scintillation, it is easy to see why it the brilliant cut is the number one choice for diamond engagement rings. The round brilliant cut diamond is the most brilliant of all the modified brilliant cuts, which include the pear cut, oval cut and marquise cut. The brilliant cut diamond offers unrivalled brilliance, and looks exquisite set in all jewellery, to include wedding rings, eternity rings, tennis bracelets, necklaces and brooches.

Round Brilliant Cut Diamond

The modern round brilliant cut has 58 facets, with 33 sparkling facets on the crown and face and 24 on the pavilion facets. Brilliant cut diamonds also feature a culet facet, at the point where the pavilion facets meet.

This diamond cut is designed to maximize brilliance, fire and scintillation from a diamond. But what do these terms mean? The way that a diamond interacts with light is dictated by the way that its facets are arranged and cut. Brilliance is defined as the brightness resulting from the reflection of light from a gemstone when viewed from above. Fire is best described as the breaking up of white light into spectral colours when it passes through a cut gemstone. Finally, scintillation is the sparkle of the diamond. The modern round brilliant cut boasts the ideal balance of these three factors to deliver the most visually pleasing optical effects.

The modern round brilliant cut diamond has been a work in progress since diamonds were first cut. For hundreds of years, variations on facets and shapes have been cut in attempts to maximize the brilliance and fire of a rough diamond crystal. It was in 1919 that a 19 year old Marcel Tolkowsky produced a thesis on the ‘American Ideal Cut’ and the modern round brilliant cut was born. In his work, Tolkowsky conducted precise mathematical calculations on facet proportions and angles for a diamond, resulting in what was called the American Ideal Cut. This cut formed the basis for the modern round brilliant cut. Following on from Tolkowsky’s work, in 1970 the International Diamond Council produced a set of ideal ranges for round brilliant cut diamonds. The girdle diameter is classed as 100%, and the ranges below are calculated in relation to this. The cut grade assigned to any round brilliant cut diamond will give an indication of these proportions, so we would recommend any stone with a grading of good and above.


Ranges for a well cut round brilliant cut diamond

Crown Angle


Crown Height


Pavilion Angle


Pavilion Depth


Table Width


Girdle Thickness

Thin to Slightly Thick

Culet Facet

None to Very Small

The round brilliant cut diamond is a classic and versatile cut. It makes a spectacular choice for diamond jewellery, and its interaction with light is unrivalled.

Contact our team of diamond jewellery specialists for more advice on diamond cuts. Buy round brilliant cut diamond engagement rings and jewellery online with 0% interest free finance and free UK delivery. Call us on 01335 453 453 or email us at