Elongated Cushion Diamonds and the L:W Ratio – Mapple Gems

Lab Grown Diamonds

Elongated Cushions and the Ratio Nobody Prints

A cushion can be square or distinctly long, and the report never says which — you have to work it out.

Written by the Mapple Gems workshop, Surat · Updated 3 October 2026

Short answer

Divide length by width on the measurements line — the ratio is never printed. Around 1.00–1.05 is a square cushion; 1.15–1.25 reads gently soft; 1.30–1.45 is what sellers mean by “elongated”, though the word has no threshold and no definition. An elongated cushion buys length by giving up width, so it covers less finger than a square one at the same weight — and it usually needs a contour band where a square cushion does not.

Cushion is the least standardised shape in the trade. Two stones can share a name, a carat weight and a set of grades and look almost nothing alike — and the ratio is half of why.

Elongating a stone does not add material — it moves it, so a longer cushion is a NARROWER cushion, and it covers less of the finger rather than more. Weight is fixed by the carat figure, so stretching the outline along one axis takes width from the other. At two carats a cushion at a 1.05 ratio measures roughly 7.4 × 7.0 mm, while the same weight at 1.40 measures roughly 8.7 × 6.2 mm. The elongated stone is over a millimetre longer and almost a millimetre narrower. Which one looks bigger depends entirely on what you are asking for: if you want the finger to look longer, buy length; if you want the stone to look large, buy WIDTH, because the eye reads apparent size across the finger far more than along it. Nearly everyone assumes elongated means bigger, and on the axis most people actually notice, it is the opposite. This is also why an elongated cushion frequently needs a contour band and a square one frequently does not — the stone extends past where a straight band wants to sit.

Ratios and what they read as

L:W ratio	Reads as	At 2 ct, roughly
1.00 – 1.05	Square cushion	7.4 × 7.0 mm
1.10 – 1.20	Softly rectangular	7.9 × 6.8 mm
1.25 – 1.35	Clearly elongated	8.4 × 6.5 mm
1.40 – 1.50	Long; reads near-oval	8.7 × 6.2 mm
1.55+	Losing the cushion character	9.1 × 5.9 mm

Treat the millimetres as indicative — depth and cut change them — but the direction is reliable, and it is the part that surprises people.

The word means nothing on its own

There is no industry threshold for “elongated”. Sellers apply it anywhere from about 1.15 upward, and two listings using the same word can be a noticeable distance apart on the hand.

So do the arithmetic yourself. The measurements line on any report gives length × width × depth; divide the first by the second. It takes ten seconds and it is the only version of the number that is hers rather than the seller’s.

And ask for a face-up photograph on a plain background, because the ratio describes a bounding box rather than an outline. Two stones at 1.30 can differ visibly: one holding its width to the ends, another tapering early and reading sharper and smaller.

Ratio is only half the question

The other half is the faceting, and the two are independent — which is exactly why cushions vary so much more than any other shape.

A crushed-ice cushion has many small facets producing a scattered, glittering look. A chunky or antique cushion has fewer, larger facets giving broad slow flashes. Elongating either is possible, so “elongated cushion” describes only the outline and tells you nothing about how the stone behaves.

Ask both questions together: what is the ratio, and is it crushed ice or chunky? A seller who can answer the second one has actually looked at the stone.

Practical consequences

Band fit. Run the straight-edge test against the side elevation before casting — visible daylight means a contour band, and above about 1.25 that is common. Order the band with the ring.
Corners still need prongs. A cushion’s corners are rounded rather than cropped, but they remain the thinnest points of the girdle. Four prongs to about two carats, six above.
No cut grade exists. Cushion is a fancy shape, so no laboratory grades cut — rotating video in ordinary indoor light is the grading.
Watch the centre. Badly cut cushions go flat and dead in the middle, and a longer outline gives that more room to show. It appears in video and in no still photograph.
Check measurements against standard. Larger than expected for the weight means the stone was spread shallow.

Which to choose

Genuinely a matter of what you want the ring to do. Square cushions read as substantial, sit comfortably with a straight band, and suit anyone who wants presence across the finger. Elongated cushions flatter a shorter finger, work beautifully east-west, and give an antique-adjacent softness that an oval does not.

One steer we would give: if the hand is small, apparent size is a ratio rather than a millimetre figure — 6.5 mm of width on a size 4 reads as 7.5 mm would on a size 7. Buy width, not weight.

Keep reading

Frequently asked questions

What ratio makes a cushion elongated?

There is no industry threshold — sellers apply the word from about 1.15 upward. Roughly 1.25–1.35 reads clearly elongated and 1.00–1.05 is square. Divide length by width on the measurements line yourself; the ratio is never printed on a report.

Does an elongated cushion look bigger?

Longer, but narrower — weight is fixed, so stretching one axis takes width from the other. The eye reads apparent size across the finger more than along it, so a square cushion often looks larger. Buy length to lengthen the finger, width to make the stone look big.

Does an elongated cushion need a contour band?

Often, above about a 1.25 ratio, because the stone extends along the finger past where a straight band sits. Run the straight-edge test against the CAD side elevation before casting, and order the band with the ring rather than commissioning one later.

Is elongated the same as crushed ice?

No — they are independent. Elongation describes the outline; crushed ice versus chunky describes the faceting and how the stone behaves in light. Either faceting can be elongated, so ask both questions: what is the ratio, and which faceting is it?

Tell us the ratio you want, not just the shape.

On a cushion it changes the stone more than the carat figure does — and no listing states it.

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