Cushion Cut Diamonds: The Complete Guide

What is a cushion cut diamond?

A cushion cut diamond is a square or rectangular brilliant with rounded corners and gently curved sides, so the outline looks like a pillow. It is a brilliant cut, meaning its facets are triangles and kites angled to send light back up as brightness and sparkle, rather than the long parallel step facets you see on an emerald or Asscher cut.

It belongs to the square and cushion family of cuts alongside the princess, radiant and Flanders, and it is one of the 34 diamond cuts we explain and compare. If you have not settled on a shape yet, our overview of every diamond shape is a good place to begin.

Cushions vary more than almost any other shape. Three things decide how a particular stone looks: the faceting pattern (brilliant or modified), the outline (square or elongated, with tight or soft corners) and the depth. The outline alone comes in several styles:

• Square cushion: length and width almost equal, a ratio of about 1.00–1.05. The classic engagement ring look.
• Elongated cushion: noticeably longer than it is wide, usually 1.15–1.35, which slims the finger.
• Tight corners: a crisper, more square-cornered outline, closer to a radiant.
• Soft or pillowed corners: rounder corners and bowed sides, the more traditional, vintage-looking cushion.

Any unfamiliar term in this guide, from pavilion to culet, is also defined in our jewellery glossary of trade terms.

Where does the cushion cut come from?

The cushion is the modern descendant of the old mine cut, the main diamond shape of the 1700s and 1800s. Old mine diamonds were cut by hand, by eye, to save as much weight as possible from the rough crystal. They have a high crown, a small table (the flat top facet), a deep pavilion (the lower half) and a large, open culet, which looks like a small circle in the centre when you look down through the stone.

Before brilliant faceting took over, many diamonds were rose cut, with a flat base and a domed top of triangular facets; our comparison of rose cuts and brilliant cuts explains how the two handle light. The old mine was an early form of the brilliant, with a fully faceted pavilion underneath rather than the rose cut's flat base, and the famous Hope Diamond is an antique cushion of this style.

Today's cushion keeps the old mine's soft outline but is cut with modern equipment: a larger table, a smaller or no culet, tighter symmetry and angles planned for brightness. If you love the antique look, our guide to old mine versus modern cushion diamonds shows the differences side by side.

What is the difference between cushion brilliant and cushion modified?

This is the most important choice with a cushion, and most buyers never hear about it. GIA reports describe cushions in two main ways: Cushion Brilliant and Cushion Modified Brilliant. The difference is on the pavilion. A cushion brilliant has one row of large pavilion main facets, usually 58 facets in total. A cushion modified adds an extra row of facets underneath, often splitting the mains, which breaks the light into many smaller flashes.

In practice there is a spectrum. Some modified cushions are hybrids with a chunky centre and crushed ice towards the edges, and the report wording will not tell you which you have. Our guide to cushion modified and crushed ice diamonds covers that style in depth, and chunky facets versus crushed ice shows photos of each so you can decide which look you prefer.

What is the best ratio for a cushion cut diamond?

The length-to-width ratio is the stone's length divided by its width, taken from the measurements on the report. A cushion of 6.20 × 6.00 mm has a ratio of 1.03, which reads as square. There is no single correct ratio; it depends on whether you want a square or an elongated look.

The awkward middle zone, roughly 1.05 to 1.12, is where many cushions fall because cutters save weight that way. They are often good value, but put one beside a true square and a true elongated stone before deciding. Our guide to elongated cushion cuts goes further, and if you are torn between a long cushion and an oval, see how ovals and elongated cushions differ.

How deep should a cushion cut diamond be?

Depth is the stone's total height as a percentage of its width. Cushions are often cut deep, because a deep cushion keeps more weight from the rough crystal. The catch is that weight sits underneath, in the pavilion, where you cannot see it. A 1 carat cushion at 72% depth can face up like a 0.85 carat stone at 64%. GIA gives cushions no overall cut grade, so the proportions are yours to check.

These are guide ranges, not rules; a well-cut cushion at 69% can still look bright. Our cushion proportions chart lists the numbers for chunky and crushed ice stones separately, and how depth hides weight in a cushion shows the face-up difference with real measurements.

For comparison, a 1 carat round brilliant is about 6.4–6.5 mm across, so a cushion of the same weight usually looks a little smaller. The smaller end of each range is a deeper stone; the larger end is closer to 63–65% depth.

What colour and clarity should a cushion diamond be?

Cushions show body colour (the natural tint of the diamond) more than rounds, especially crushed ice cushions and stones with soft corners, because light is concentrated towards the corners and the faceting does not mask warmth as well. Our article on why cushions can show more body colour explains the optics.

• White gold or platinum: H colour or better for most people; G or better if you are sensitive to warmth or choosing an elongated stone over 1.5 carats.
• Yellow or rose gold: I or J usually looks just as white, because the metal warms everything around it.
• Antique look: some people deliberately choose J–K for the warmer, candle-lit feel of an old mine stone.

For clarity, the goal is an eye-clean stone, meaning you cannot see inclusions without magnification at a normal viewing distance. In a crushed ice cushion, a carefully chosen SI1 is often eye-clean because the glitter disguises small crystals. In a chunky cushion brilliant, the larger facets act like windows, so VS2 is a safer starting point. Check the corners too: an inclusion near a corner is harder to hide under a claw and sits in a more exposed part of the stone.

Cushion vs round, radiant, princess and Asscher: how do they compare?

The round is the brightest shape and looks largest per carat; our round versus cushion comparison weighs that against the cushion's softer outline and lower price per carat. The princess cut is the sharp-cornered square option, while the radiant cut has cut corners and crushed-ice style faceting, so it can look very like a modified cushion.

If you prefer step facets and a more geometric, vintage look, compare the cushion with the Asscher in our Asscher versus cushion guide. The Flanders cut, a square brilliant with cut corners, is a rarer alternative in the same family.

What are the best settings for a cushion cut diamond?

A cushion has no sharp points, so it is one of the more forgiving shapes to set and to wear every day. The setting mostly changes how the outline reads:

• Four claws: one at each corner shows the full pillow outline. Double claws add security and a slightly vintage look.
• Halo: a cushion halo makes the centre look larger and can hide a little warmth by surrounding it with white diamonds. It is the most common cushion setting.
• Hidden halo: a row of small diamonds under the stone, visible from the side, keeping a clean solitaire look from above.
• Bezel: a thin rim of metal, very secure, though it covers some of the soft edge.
• Three-stone: trapezoid, pear or round side stones beside a cushion centre; check the side stones match the centre's colour.

Claw orientation matters for elongated stones: set north-south (length along the finger) to slim the hand, or east-west for a more modern look. Our guide to settings that suit cushion diamonds compares each style with examples.

Should you choose a natural or lab-grown cushion cut diamond?

Cushions are cut from both natural and laboratory-grown diamond, and the two look identical to the eye; only specialist equipment can tell them apart. Lab-grown diamond has the same chemistry, hardness (10 on the Mohs scale) and refractive index (2.42) as natural diamond. Lab-grown cushions cost much less and are easy to find in larger, well-proportioned sizes; natural cushions are rarer, and natural stones in this shape are often cut deeper to save weight, so measurements matter even more.

As a rough guide, a 1 carat natural cushion in G–H colour and VS2 clarity tends to sit somewhere around AUD 6,000–12,000, while a lab-grown cushion of similar grades is often in the region of AUD 800–2,500. Prices move with the market, and cut quality, depth and the chunky or crushed ice style all shift the figure within those ranges. A cushion usually costs less per carat than a round of the same weight, colour and clarity.

Whichever you choose, ask for an independent grading report (GIA or IGI are the most common) and real photos or a 360° video of the actual stone, not a stock image.

How to choose a cushion cut diamond: step by step

1. Pick the look first. Decide between chunky and crushed ice by watching videos of both, then choose square (1.00–1.05) or elongated (about 1.15–1.35).
2. Read the report. Note whether it says Cushion Brilliant or Cushion Modified Brilliant, plus measurements, colour, clarity, polish and symmetry.
3. Work out the ratio. Divide length by width from the measurements and check it sits in the range you want.
4. Check depth and face-up size. Aim for about 61–68% depth; compare the millimetre width with other stones of the same carat.
5. Watch a 360° video. Look for a dark centre, visible inclusions near the corners and how strongly the corners show colour.
6. Match colour to metal. H or better in white metal, I–J in yellow or rose gold, then plan the setting around the stone.