ANATOMY OF A RADIANT CUT DIAMOND
About The Radiant Cut (Classic Rectangular & Square Shapes)
Designed by Henry Grossbard in 1978, the radiant cut blends the expressive shape of the emerald cut with the sparkling brilliance of a round cut diamond.
The seventy facets of this diamond cut create a sublime radiance, with cut corners and an elongated shape making this a particularly popular choice.
The radiant cut may also be referred to as the radiant brilliant cut, as with it's multiple facets it displays a sparkle more akin to the round brilliant cut.
Pavilion Facet Pattern
Radiant diamonds vary in exactly how their facets are cut. Of the multiple radiant pavilion facet patterns, the ideal choice is the "long mains" pattern.
"Short mains" patterns introduce extra facets that interrupt the light and can result in slightly less definition. However, the "long mains" pattern has larger facets that produce bigger flashes of light.
In the “long mains” pavilion facet pattern shown in yellow, the pavilion facet mains (highlighted) extend all of the way to the edge of the diamond.
As a result, the long mains pattern shows more scintillation and has better light performance (sparkle). Put simply, the longer the mains pattern the better.
Cut-Corners Of The Radiant Cut
Dimensions including percentage table and depth, and length-to-width ratios impact how the diamond looks and how much light it reflects.
In the case of the radiant cut, the perfect table should be between 63% and 70%. The ideal depth is between 65% and 70%.
Length To Width Ratio
The ideal length-to-width ratio is generally considered to be between 1.25 and 1.40, with a ratio of 1.15 to 1.24 or 1.41 and 1.46 classed as very good.
As with other shaped diamonds such as the emerald or oval cut, the length-to-width ratio is essentially a matter of personal choice and not a specific grading criteria featured in a GIA or IGI report.
Nevertheless, in selecting a radiant cut stone, a ratio which is much below 1.15 will mean that the diamond appears almost square. A higher ratio much above 1.46 describes a diamond which is "longer" and marginally narrow.
Length To Width Ratio 1.34
In the case of a square radiant diamond, the ideal ratio is between 0.99 and 1.04.
Colour & Clarity
Any minor marks or inclusions found in the middle of the stone will not be so clearly visible in a radiant cut diamond as it is in many other shapes. It is therefore not necessary to pay a premium for a clarity grade above VVS2.
This is because the high number of facets cut into the face-up area of the diamond reflect and disperse more light throughout the stone.
As a function of the large surface area of the stone, the diamond colour tends to be more detectable. In this regard, we would advise against choosing a radiant cut with a colour grading below H.
In summary, if budget allows, we would guide towards a radiant cut diamond with a ratio between 1.22 and 1.44, with colour F and clarity VS2 or higher.