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At the same carat weight and ratio, an elongated cushion and a radiant are the same size: both measure about 6.2 × 4.8 mm at 1 carat when cut to a 1.30 length to width ratio. What separates them is the outline and the light. An elongated cushion has softly rounded corners and a romantic, antique feel; a radiant has straight sides with cropped corners and a brighter, crushed-ice sparkle.
They end up on the same shortlist for good reason. Both are rectangles, both flatter the finger the way an oval does, and both protect their corners, so both wear well every day. This guide sets them side by side on size, on the hand, and on the details that make one feel vintage and the other modern.
Length by width in millimeters at each carat weight, at the proportions we cut them to. The oval and round are included for comparison.
| Carat | Elongated cushion (mm) | Radiant (mm) | Oval (mm) | Round (mm) |
|---|---|---|---|---|
| 0.75 ct | 5.7 × 4.4 | 5.7 × 4.4 | 7.0 × 5.2 | 5.9 × 5.9 |
| 1.00 ct | 6.2 × 4.8 | 6.2 × 4.8 | 7.7 × 5.7 | 6.5 × 6.5 |
| 1.50 ct | 7.1 × 5.5 | 7.1 × 5.5 | 8.8 × 6.5 | 7.4 × 7.4 |
| 2.00 ct | 7.9 × 6.0 | 7.9 × 6.0 | 9.7 × 7.2 | 8.2 × 8.2 |
| 2.50 ct | 8.5 × 6.5 | 8.5 × 6.5 | 10.4 × 7.7 | 8.8 × 8.8 |
| 3.00 ct | 9.0 × 6.9 | 9.0 × 6.9 | 11.1 × 8.2 | 9.4 × 9.4 |
| 4.00 ct | 9.9 × 7.6 | 9.9 × 7.6 | 12.2 × 9.0 | 10.3 × 10.3 |
| 5.00 ct | 10.7 × 8.2 | 10.7 × 8.2 | 13.2 × 9.7 | 11.1 × 11.1 |
The first two columns match because we cut both shapes to a classic 1.30 ratio with the same proportions. Both are a little shorter than a round of the same weight, 6.2 mm against 6.5 mm at 1 carat, because they carry more of their weight in depth. Doubling the weight from 1 to 2 carats takes either shape from 6.2 × 4.8 mm to 7.9 × 6.0 mm.
An elongated cushion is a cushion cut stretched into a rectangle. It keeps the rounded corners and gently curved sides of the square cushion, so the outline looks soft, like a pillow. On a grading report it is simply called a cushion, and the length to width ratio in the measurements tells you it is the elongated kind.
A radiant has straight sides and cropped corners, the outline of an emerald cut filled with brilliant faceting instead of steps. From across a room it reads as a crisp, geometric rectangle. Up close it behaves like a brilliant.
Neither shape has a sharp point to catch or chip. The cushion's corners are rounded; the radiant's are cut away. That makes both of them among the most practical choices for a ring worn every day.
Both shapes are brilliant cuts, so both sparkle rather than showing the long mirrored flashes of an emerald or Asscher. The character of that sparkle is different. An elongated cushion throws broader, softer flashes, a warm light that recalls the old mine cuts it descends from. A radiant, with around 70 facets, breaks light into many small, bright pieces, which is where the crushed-ice description comes from.
If you love vintage rings, the cushion usually wins. If you want the most energetic sparkle in a rectangular outline, the radiant does.
For both shapes, the length to width ratio decides how long the stone looks. An elongated cushion usually sits between about 1.15 and 1.35, and an elongated radiant between about 1.30 and 1.50. Here is the same 1.5 carat stone at different ratios. The weight stays fixed, so a longer stone is also a narrower one.
| Ratio | Length × width (mm) | How it reads |
|---|---|---|
| 1.15 | 6.6 × 5.7 | Gently rectangular |
| 1.20 | 6.8 × 5.6 | Clearly a rectangle |
| 1.25 | 7.0 × 5.6 | Decisively long |
| 1.30 | 7.1 × 5.5 | Classic elongated, our standard |
| 1.40 | 7.5 × 5.4 | Long; the upper end for a cushion |
| 1.50 | 7.9 × 5.2 | Long radiant |
Find Me Diamond has a ratio control for both shapes, so you can set the exact ratio of a stone you are considering and see it on your finger.
Set north-south, a 1 carat elongated cushion or radiant is 4.8 mm across the finger and covers about 28% of the width of a US size 6.5 finger, against 38% for a 1 carat round. At 2 carats it is 7.9 × 6.0 mm and covers about 36%. That narrower footprint is what makes both shapes look slender and lengthen the finger.
If you are also weighing an oval, the numbers favor the oval on size: at 1 carat it measures about 7.7 × 5.7 mm, longer and wider than an elongated cushion at 6.2 × 4.8 mm. The oval has no corners at all and a smooth, continuous outline. The elongated cushion keeps a hint of the rectangle and a softer, more vintage light.
Choose the elongated cushion if you want romance and softness: rounded corners, broad warm flashes and a look that sits comfortably with vintage and hidden halo designs. Choose the radiant if you want a crisp, modern rectangle with a lively, bright sparkle. At the same weight and ratio you are not trading size either way, so the decision is purely about the look you love.
At the same weight and ratio they are the same size: both measure about 7.1 × 5.5 mm at 1.5 carats when cut to a 1.30 ratio. Real stones vary a little with cut depth, so compare the measurements of the actual stones rather than the shape names.
A radiant has around 70 facets that break light into many small, bright flashes, the crushed-ice look. An elongated cushion throws broader, softer flashes with a warmer, antique feel. Neither sparkles more in any absolute sense; they sparkle differently, so choose the light you prefer.
Both are durable, because neither has a sharp corner: the radiant crops all 4 of its corners and the elongated cushion rounds them. That makes either one a sensible choice for a ring worn every day, in a prong or a bezel setting.
Around 1.25 to 1.35 is where an elongated cushion looks decisively long; at a 1.30 ratio a 1.5 carat stone measures about 7.1 × 5.5 mm. Below about 1.10 it reads square, and above about 1.40 it starts to look like a different shape. The ratio you like is personal, so compare two at actual size.
No: at 1 carat an oval measures about 7.7 × 5.7 mm and an elongated cushion 6.2 × 4.8 mm, so the oval is both longer and wider for the same weight. The oval spreads its weight across a larger face; the elongated cushion carries more of it in depth.
See both at actual size on your own ring size: open an elongated cushion at 1.5 carats in Find Me Diamond, then a radiant of the same weight, and try the ratio control on each. Read the full elongated cushion guide and radiant guide, and browse lab grown diamond engagement rings or 2 carat engagement rings. Every Ronora diamond is a real CVD lab grown diamond, Excellent cut, D-E-F colorless with VVS clarity, made to order in Surat.
