Radiant Cut Diamonds

People usually arrive at the radiant from one of two directions. Either they love the clean rectangle of an emerald cut but miss the sparkle, or they love the fire of a round but want something less traditional. The radiant answers both.

It belongs firmly to the brilliant family of faceting styles, which the International Gem Society separates from step cuts. That is the whole trick of the shape: it looks like a step cut from across a room and behaves like a brilliant in your hand.

A radiant is a rectangular or square stone with cropped corners and brilliant-style faceting, usually carrying around 70 facets. The extra facets compared with a round are what give it its particular crushed-ice sparkle: light breaks into many small pieces rather than a few large flashes.

The cropped corners matter more than they look. They remove the four weak points that make a princess vulnerable, which makes the radiant genuinely hard-wearing. There is nothing on the stone that can catch and chip.

Length-to-width ratio decides whether it reads as square or rectangular. Around 1.00 to 1.05 gives a square radiant. Around 1.30 to 1.50 gives the elongated version, which is the more popular of the two and flatters the finger the way an oval does.

The radiant is a modern invention with a clear author. It was created in 1977 by Henry Grossbard, a New York cutter who set out to solve a specific problem: rectangular diamonds looked beautiful but died in the middle, because step cutting simply does not return as much light as brilliant cutting.

His solution was to keep the emerald cut's outline and throw away its facet structure entirely, replacing it with a brilliant arrangement. It was the first cut to successfully combine the two, and everything in that family since, including the elongated cushion, owes something to it.

These are two quite different rings. A square radiant at a ratio near 1.00 sits compact and bold, closer in feel to a princess. An elongated radiant at 1.30 or above stretches along the finger and reads much closer to an oval.

Neither is better. But they photograph differently, they suit different hands, and they pair with different bands, so it is worth settling this before looking at anything else.

Radiants are not given an overall cut grade, so read the numbers. Depth between roughly 61% and 70% with a table around 61% to 69% gives the best light return. Too deep and the stone loses spread without gaining brilliance.

The other thing to know is that radiant faceting produces a crushed-ice look: many small sparkles rather than a few broad flashes. Some people love it; others prefer the larger, cleaner flashes of a round. It is a genuine preference, not a quality issue. Every Ronora radiant is Excellent cut.

This is where the radiant genuinely beats its relatives. All that brilliant faceting breaks light up fast enough to swallow small inclusions and mask slight warmth, which a step cut of the same outline could never do. If you want a rectangular diamond but do not want to pay step-cut prices for clarity, the radiant is the sensible answer.

It is also the reason radiants are so often used for fancy coloured diamonds: the faceting concentrates and intensifies colour rather than diluting it. Our fancy yellow and fancy green radiants exist for exactly that reason. Standard Ronora radiants remain D-E-F colourless.

A radiant carries more weight in its depth than an emerald cut of the same outline, so it spreads slightly less face-up for the same carat. An elongated radiant recovers most of that through its length, and on the hand the difference is small. Our diamond measurements guide shows the millimetre size at every carat weight, drawn at true scale.

It uses rough efficiently, which keeps the price per carat below a round. Because it hides inclusions and warmth so well, this is one of the few shapes where spending on carat weight rather than on the top of the clarity scale is genuinely defensible, though every Ronora stone stays within our ladder regardless.

See a radiant cut at actual size on your own ring size, or as a stud or pendant, with Find Me Diamond, our free diamond size visualizer.

With no fragile points, a radiant can be set almost any way you like. The decision is about what you want the shape to say.

• Four prong solitaire. Prongs on the cropped corners, nothing else. Shows the outline cleanly and lets the faceting do the work.
• Halo. Very effective here. A frame of small rounds pushes an already generous outline larger and amplifies the crushed-ice sparkle.
• Three stone with tapered baguettes. Straight side stones reinforce the rectangle and give a strong Art Deco line, particularly on an elongated radiant.
• Pavé shank. Fine pavé along the band suits the radiant's busy sparkle better than it suits a step cut, where it would compete.
• Bezel. A full rim traces the cropped corners neatly and gives the most secure, most minimal result.

What it does well

• Combines a rectangular outline with brilliant-cut fire, which no step cut can do.
• Cropped corners make it one of the most durable shapes available.
• Hides inclusions and warmth better than any angular alternative.
• Available square or elongated, so it suits very different tastes.
• Intensifies fancy colour, which is why coloured diamonds are so often cut this way.

What to watch

• Crushed-ice sparkle is divisive. Some prefer the broader flashes of a round.
• Carries weight in its depth, so it can spread less than an emerald of the same carat.
• No official cut grade, so proportions must be read individually.
• Square and elongated radiants are very different rings; decide which you mean.