The radiant cut is the name used to describe the cut-cornered, rectangular or square modified brilliant cut diamonds.
While some radiant cut diamonds have 70 facets (25 on the crown, 8 on the girdle and 37 on the pavilion), the most common facet pattern has 62 facets (25 on crown, 8 on the girdle, and 29 on the pavilion). The truncated corners help to minimize chipping. The radiant cut diamond is the first rectangular cut to have a complete brilliant facet pattern applied to both the crown and pavilion and so has more brilliant to the diamond compared to an emerald cut.
In the rectangular radiant cut, as with marquise shapes and other long fancy shapes, there is an increased likelihood of having a 'bow tie.' This is a dark area in the shape of a man's bow tie that occurs when the angles of the cut are not optimum. This facet misalignment can detract from the brilliance, especially if it is an exaggerated or overly dark bow tie effect.
Radiant cut diamonds with the same width do not have the same surface area. For example, a radiant cut diamond having a width of 5 mm and length of 7 mm has a surface area of 35 square millimeters. A radiant cut diamond with the same 5 mm width and a length of 5 mm has a surface area of 25 square millimeters. To maximize the beauty of each diamond, the radiant cut diamond with the greater surface area requires a greater depth percentage. The bottom line is that more rectangular radiant cut diamonds should have greater depth percentages than those that are closer to being square.
Radiant cut diamonds are especially popular for fancy-color diamonds because the shape, proportioning and facet arrangement intensify the color. Other diamond shapes tend to have lighter areas than others as the facet patterns do not show color evenly throughout the stone. The fancy color radiant cut diamonds usually have lower length-to-width ratios that are closer to a square than a rectangle.