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Cut Reference  ·  No. 008

Radiant
Cut

Radiant Brilliant  ·  70 Facets  ·  Trimmed Corners

The rectangle that sparkles. Emerald's silhouette, brilliant's fire — and a 1977 patent that changed how the industry thought about fancy shapes.

The radiant cut is a rectangular or square brilliant with trimmed corners — the same octagonal outline as an emerald cut, but with a completely different internal facet structure. Where the emerald uses parallel step facets to produce a slow, architectural light pattern, the radiant uses a brilliant-style arrangement of 70 triangular and kite-shaped facets to produce high-energy sparkle across the entire face. It is the only rectangular shape that combines emerald's silhouette with brilliant-level light performance — and the clarity requirements are far more forgiving as a result.

Origin

The radiant cut was patented by New York cutter Henry Grossbard in 1977, who spent years developing a facet arrangement that could apply brilliant-cut optics to a rectangular outline. His "radiant cut" was the first modified brilliant specifically designed for the rectangular shape — a category that had previously been dominated entirely by step cuts. The patent expired in the 1990s, after which the design was widely replicated and refined by cutters worldwide, and it has grown significantly in popularity alongside the broader revival of elongated shapes in the 2010s–2020s.

On The Hand
Elongating
The rectangular outline with trimmed corners creates a strong elongating effect — less dramatic than marquise or pear but more defined than cushion. The trimmed corners eliminate the chip risk of a princess's sharp corners while maintaining a clean rectangular silhouette. Works well across most hand types.
70
Facets
1977
Grossbard Patent
−15%
vs. Round
1.00–1.35
Ideal L:W Ratio
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Radiant Cutthecutguide.com
Specifications
Table Percentage
58 – 69%
More forgiving than round. The brilliant facet structure compensates for table variation more effectively than step cuts.
Depth Percentage
61 – 74%
Radiants run deeper than emerald cuts. The brilliant faceting requires this depth for proper light return.
Length-to-Width Ratio
1.00 – 1.35
Square (1.00–1.05) or elongated (1.20–1.35). The elongated version is the one most often compared to emerald cut.
GIA Cut Grade
—
Fancy Shape
Far more forgiving on clarity than emerald cut. SI1 is often acceptable — a significant advantage over the step-cut alternative.
Polish / Symmetry
Exc / Exc
Both Excellent. The brilliant structure is more forgiving than step cuts but Exc/Exc remains the target.
Light Performance
Brilliance86
Fire84
Scintillation84
Size per Carat86
Clarity Concealment84
Budget
vs. Round Brilliant
−15 to −20%
Genuine discount relative to round. The clarity forgiveness of radiant vs. emerald cut means you can often spend less on clarity here than you would on an equivalent emerald.
Lab-Grown Radiant
−40 to −55%
G, VS2 target spec — though SI1 is often viable on this shape. Lab-grown radiant represents strong value for buyers who want a rectangular brilliant without step-cut clarity requirements.
What Retailers Won't Tell You
⚠ Not All Radiants Are Equal in Depth
Radiant cuts can be cut with depths ranging from 61% to 80% — a significant range that dramatically affects face-up size. A 1.50ct radiant at 74% depth may face up smaller than a 1.20ct radiant at 64% depth. Always request millimeter face-up dimensions from the lab report, not just carat weight. Depth hides more weight on radiants than almost any other brilliant cut.
⚠ "Radiant vs. Emerald" Is a Lifestyle Choice
Buyers often compare radiant and emerald cuts because they share an outline. They are optically opposite. Emerald is slow, architectural, and unforgiving on clarity. Radiant is bright, active, and clarity-tolerant. Neither is better — but choosing the wrong one for your preference is a common and expensive mistake. View both in person before deciding.
The Cut Guide  ·  Assessment  ·  Radiant Cut
"Grossbard's solution to a problem the industry didn't know it had: what if you wanted a rectangular diamond that actually sparkled? The radiant delivers brilliant-cut performance in an emerald-cut silhouette — with significantly more forgiving clarity requirements and no bowtie. It is not as architecturally refined as an emerald, nor as brilliant as a round. It is, by design, exactly in between."
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