Last updated on February 4, 2021
Being popular since the 1980s, radiant is the first angular shape that has a complete brilliant-cut facet pattern. In fact, radiant is one of the most faceted and brilliant diamond cuts available on the market. If you are interested in buying a diamond with a vibrant look and brilliance, our radiant cut diamond guide is a must-read.
History of Radiant Cut Diamonds
The original radiant cut was invented by a master diamond cutter Henry Grossbard in 1977.
Grossbard knew that many people loved the elegant elongated shape of the emerald cut but felt that it didn’t sparkle enough. His goal was combining the best features of the emerald cut and the round brilliant cut into one diamond cut that would unleash the full potential of a diamond’s brilliance.
After years of careful experimentation, Grossbard perfected the radiant cut in 1981. This was a revolution in the diamond industry, the elegant emerald shape was transformed into a new cut with unparalleled sparkle. Although it did not exceed the round brilliant cut’s brilliance, it is still more brilliant than any other angular cut.
Featuring 70 brilliant-cut facets, radiant cut diamonds come in both rectangular and square shapes with cropped corners.
Even though the radiant cut has only been in the diamond industry for 44 years, it managed to gain extreme popularity in a short amount of time.
Radiant Cut Diamond Cut Quality Guide
Diamond cut quality is the main factor determining a stone’s appearance and level of brilliance and sparkle.
Since the GIA (Gemological Institute of America) doesn’t provide cut grading for radiant cut diamonds, you will need to be very careful when selecting one.
Make sure you have checked the corners, they should be even, not too wide or too narrow. The symmetry is the key to maintain the overall beauty of the stone.
The table below will serve you as a general guideline for evaluating the cut quality of the radiant cut diamonds.
| EXCELLENT | VERY GOOD | GOOD | FAIR | POOR | |
|---|---|---|---|---|---|
| TABLE % | 61 - 69 | 57 - 60 or 70 - 72 | 54 - 56 or 73 - 74 | 51 - 53 or 75 - 79 | < 51 or > 79 |
| DEPTH % | 61 - 67 | 59 - 60.9 or 67.1 - 70 | 57 - 58.9 or 70.1 - 74 | 54 - 56.9 or 74.1 - 79 | < 54 or > 79 |
| GIRDLE | Very Thin to Slightly Thick | Very Thin to Slightly Thick | Very Thin to Thick | Very Thin to Very Thick | Extremely Thin to Extremely Thick |
| CULET | None | Very Small | Small | Medium | > Medium |
Radiant Cut Diamond Colour Guide
Colour of radiant cut diamonds is graded on a scale from D to Z, where D signifies a completely colourless stone and Z means an easily noticeable yellow or brown tint.
As a general rule, smaller radiant cut diamonds hide colour better than larger ones, but the differences in colour in radiant diamonds are easier to notice than in other diamond shapes. For this reason, it is recommended to opt for H colour or better to have a diamond that will appear white and colourless to the naked eye.
The chart below will help you decide on the colour grade of a radiant cut diamond.
| SIZE | EXCELLENT | VERY GOOD | GOOD | FAIR | POOR |
|---|---|---|---|---|---|
| < .50 ct. | D - G | H - I | J - K | L - M | > M |
| .51-1.0 ct. | D - F | G | H - I | J - K | > K |
| 1.0-2.0 ct. | D - F | D - F | G - H | I - J | > J |
| > 2.0 ct. | D - F | D - F | G | H - I | > I |
Radiant Cut Diamond Clarity Guide
The GIA grades clarity of radiant cut diamonds on a scale from FL to I3, where FL means a flawless stone and I3 indicates a heavily included diamond.
Due to the brilliant-cut facet pattern, radiant cut diamonds hide blemishes fairly well, especially in comparison to emerald cut diamonds. Moreover, smaller radiant cut diamonds hide imperfections better than larger ones do, which is why if you are going to purchase a smaller stone you may opt for a lower clarity grade while keeping an eye-clean appearance.
The clarity chart below provides a general guide for evaluating clarity in radiant cut diamonds.
| SIZE | EXCELLENT | VERY GOOD | GOOD | FAIR | POOR |
|---|---|---|---|---|---|
| < .50 ct. | FL - VS2 | SI1 - SI2 | I1 | I2 | > I2 |
| .51-1.0 ct. | FL - VS1 | VS2 - SI1 | SI2 | I1 - I2 | > SI2 |
| 1.0-2.0 ct. | FL - VVS2 | VS1 - VS2 | SI1 - SI2 | I1 | > I1 |
| > 2.0 ct. | FL - VVS2 | VS1 - VS2 | SI1 | SI2 | > SI2 |
Radiant Cut Diamond Ratio Guide
The length to width ratio expresses how relatively long or wide a diamond appears. It is calculated by dividing the length of the diamond by its width.
Each fancy diamond shape has a certain length to width ratio that is considered most appealing for that shape. Radiant cut diamonds come in various ratios, from perfectly square (any ratio of 1.05 or less will appear square to the naked eye) to the more traditional rectangle.
The optimal ratio for radiant cut diamonds is between 1.00-1.35; however, rectangular shapes’ ratios can go up to 2.00.
The table below serves as a general guideline for evaluating the ratio of a radiant cut diamond.
| EXCELLENT | VERY GOOD | GOOD | FAIR | POOR | |
|---|---|---|---|---|---|
| SQUARE | 1.00 - 1.03 | 1.00 - 1.03 | 1.04 - 1.05 | 1.06 - 1.08 | > 1.08 |
| RECTANGLE | 1.20 - 1.30 | 1.15 - 1.19 or 1.31 - 1.35 | 1.10 - 1.14 or 1.36 - 1.40 | 1.08 - 1.09 or 1.41 - 1.50 | < 1.08 or > 1.50 |
