Its character
The outline of an emerald cut with the facet work of a brilliant — the shape that resolved the choice between a rectangular silhouette and active light return. Available square or elongated. It holds colour well, which is why it is a common choice in fancy-coloured goods.
Where the radiant cut comes from
The radiant cut was developed by Henry Grossbard in 1977. It was the first shape to apply a full brilliant facet pattern to both the crown and the pavilion of an emerald-cut outline, combining a clean rectangular shape with strong sparkle.
It became especially important for coloured diamonds, because its facet pattern tends to deepen and even out body colour.
How a radiant is faceted
A radiant typically has around 70 facets, although counts vary by cutter. The outline has cropped corners like an emerald cut, but the facets underneath are brilliant-style, producing a lively, 'crushed ice' sparkle.
Its many small facets also help hide inclusions, so a radiant can often be eye-clean at a lower clarity grade than a step cut.
Radiant cut proportions
Ranges most well-cut radiant stones fall within. They narrow the field; they do not replace seeing the stone.
| Measure | Typical range | Why it matters |
|---|---|---|
| Table | 61 – 69% | |
| Depth | 61 – 67% | Square radiants can run up to about 70%. |
| Length to width | 1.00 – 1.05 square | 1.20 – 1.35 for the elongated rectangle. |
| Girdle | Thin to slightly thick | Check the cropped corners. |
| Culet | None | |
| Cut grade | Not graded | Neither GIA nor IGI assigns an overall cut grade to this shape, so these are trade ranges rather than a standard. |
What to look for in a radiant diamond
Radiants vary widely in depth, and a deep stone can face up smaller than its weight suggests, so read the measurements alongside the carat figure. The brilliant faceting hides inclusions far better than a step cut, which often means a lower clarity grade is invisible face-up. Elongated radiants make strong solitaires; square ones sit naturally among other square cuts.
- Depth against measurements
- Radiants vary greatly in depth. Compare the millimetre measurements to the carat weight so a deep stone does not look smaller than expected.
- Dark areas
- Poorly angled radiants can show dark patches or a bow-tie in elongated stones. Check a video in good light.
- Clarity
- The brilliant faceting masks many inclusions, so SI grades can be eye-clean. Confirm by looking at the stone rather than relying on the grade.
- Outline
- Check that the corners are cut evenly and that the sides are straight and parallel.
Setting a radiant
Four prongs at the corners suit the cropped outline, and radiants look good with trapezoid, baguette or other radiant side stones. Elongated radiants make strong solitaires.
Radiant size by carat weight
Approximate face-up size at a typical radiant ratio and depth, drawn to scale. Select a weight to see natural stock in that band.
5 mm. Every silhouette is drawn to this scale, at typical proportions.
- Natural radiant diamonds, 0.25–0.49 ct, about 4.1 × 3.4 mm face up
- Natural radiant diamonds, 0.50–0.74 ct, about 5.1 × 4.3 mm face up
- Natural radiant diamonds, 0.75–0.99 ct, about 5.9 × 4.9 mm face up
- Natural radiant diamonds, 1.00–1.49 ct, about 6.5 × 5.4 mm face up
- Natural radiant diamonds, 1.50–1.99 ct, about 7.4 × 6.2 mm face up
- Natural radiant diamonds, 2.00–2.99 ct, about 8.1 × 6.8 mm face up
- Natural radiant diamonds, 3.00 ct and above, about 9.3 × 7.8 mm face up
Diamond carat guide: every shape, price milestones and choosing a weight
Terms used on this page
Each one is defined in full, with what a report prints for it, in the glossary.
- Brilliant cut
- A faceting style built from triangular and kite-shaped facets radiating from the centre.
- Depth %
- The stone's height from table to culet as a percentage of its average diameter.
- Length-to-width ratio
- The outline's proportions — length divided by width — which decides how a fancy shape reads.
- Eye-clean
- No inclusion visible to an unaided eye at normal viewing distance.
- Fancy colour
- A diamond with enough body colour to be graded for that colour rather than against D–Z.
- Measurements
- The stone's physical size in millimetres: length × width × depth.
Radiant cut questions
What buyers ask most often before choosing a radiant diamond.
What is the difference between a radiant and an emerald cut?
They share a rectangular outline with cropped corners, but an emerald cut uses long step facets while a radiant uses brilliant faceting. The radiant sparkles more; the emerald shows cleaner, broader flashes.
Is a radiant cut the same as a princess cut?
No. Both are brilliant-faceted and can be square, but a princess has sharp corners while a radiant's corners are cropped. The cropped corners are also less prone to chipping.
What clarity is eye-clean in a radiant cut?
Its faceting hides inclusions well, so many SI1 and some SI2 radiants look clean to the eye. It depends on where the inclusions are, so check the stone itself.