Cushion Cut Diamonds: A Complete Buying Guide
Two cushion cut diamonds sit on the counter. Same carat weight, same colour grade, same clarity grade, prices within two hundred dollars of each other. One throws big flashes of light you could count. The other shimmers like light on water. Buyers pick one and put the other down within about ten seconds, and most of them cannot say why. The reason is a single row of facets on the bottom of the stone, and it is the most useful thing anyone shopping for a cushion can learn.
Where the cushion came from
The cushion is old. GIA calls it one of the oldest diamond shapes and cutting styles, and points to its ancestor, the old mine cut, which dates back to the 1700s and was the most common cut until the late 19th century.
GIA lists the defining traits of an old mine cut as a squarish shape with a high crown, a small table, a deep pavilion and a large culet. Those words are worth unpacking, because three of them still shape how a modern cushion behaves.
The crown is the top half above the widest line of the stone. The table is the large flat facet on top. The pavilion is the cone below. The culet is the facet at the bottom tip, which on old stones was cut flat and wide enough to see as a small grey circle when you look straight down.
The name arrived long after the cut. GIA writes that the term old mine came into common use in the late 1800s, when diamond production from Africa began to eclipse production from the old mines of Brazil and even older mines of India. The Brazilian mines became the old ones the moment South Africa started producing. GIA describes those stones as having larger, chunkier facets that produce bold, striking flashes of colour, with less brilliance but more fire than modern cuts.
A modern cushion inherits the soft square outline and the deep pavilion. The high crown and the wide flat culet mostly went away as cutting machinery improved. If you like the antique version, our guide to the difference between antique, vintage and estate jewellery explains what those three words mean on a price tag.
The two facet patterns, and why they look nothing alike
This is the part that matters most. GIA states it in one sentence: brilliant cushions have larger facets that emphasize clarity with a softer sparkle, while modified cushions include extra facets that maximize brilliance and create a crushed ice effect.
Here is what is physically different. A standard cushion brilliant has one row of pavilion facets running from the girdle, the widest line of the stone, down toward the point. GIA notes that a cushion will typically have four or eight mains, which are kite-shaped facets between the girdle and the culet. Those mains are large. Each one acts as a single mirror, so light arrives and leaves in big pieces.
A cushion modified brilliant adds a further row of facets on the pavilion. Each large mirror is split into several smaller ones. The same amount of light comes back to your eye, chopped into many more pieces. The trade calls the result crushed ice, and the name is accurate: it looks like sunlight on a glass of finely crushed ice.
Neither pattern is a defect. They are two different products sharing one word.
| Question | Cushion brilliant (chunky) | Cushion modified brilliant (crushed ice) |
|---|---|---|
| Pavilion facets | One row of mains, typically four or eight | An extra row added below the mains |
| Light return | Broad flashes, large blocks of light and dark | Many small glints, shifting shimmer |
| GIA description | Larger facets, emphasizes clarity, softer sparkle | Extra facets, maximizes brilliance, crushed ice effect |
| Hides inclusions | Less well, large facets act as windows | Better, the busy pattern breaks up the view |
| Our clarity floor | VS2, and check the inclusion plot | SI1 is often eye clean |
| Cutting style on the report | Cushion brilliant | Cushion modified brilliant |
| Suits you if | You want antique character and visible flashes | You want continuous sparkle and a lower clarity budget |
My own preference, and this is an opinion: for a solitaire on a plain band, I reach for the chunky pattern, because the large flashes give the stone its own personality and the setting stays out of the way. For a halo, I reach for crushed ice, because the small stones around the edge are already producing small sparkles and a chunky centre can look disconnected from them. Plenty of people at our counter disagree with me and buy the opposite. Both rings leave the shop looking good.
Length-to-width ratio: square or rectangle
Length-to-width ratio is the long measurement divided by the short one. On a cushion it controls whether the stone reads as a square or a soft rectangle.
A ratio of 1.00 to 1.05 looks square. This is the traditional cushion, and it sits well in an antique-style setting with four corner prongs. From 1.10 to 1.20 the eye starts to see a rectangle, gently. Past 1.20 you have an elongated cushion, which stretches the finger visually and appeals to people who like the oval look but want softer corners.
GIA publishes suggested ratios for several fancy shapes in its fancy shape holiday buying guide, giving oval at 1.33 to 1.66 to 1, marquise at 1.75 to 2.25 to 1, pear at 1.50 to 1.75 to 1 and heart at 1.00 to 1. Cushion is absent from that list, which tells you something honest: the trade has no agreed ideal for it. You choose.
One practical note from fitting rings. An elongated cushion covers more of the finger lengthwise and can make a size 4 hand look better proportioned. A square cushion at the same carat weight looks chunkier and reads as bigger on a wider finger. Try both on the actual hand before deciding on paper.
Colour matters more in a cushion
Colour grading is done the same way for every shape, face-down against master stones under controlled light. What changes between shapes is how much of that body colour you see once the stone is face-up in a ring.
A cushion has broader facets and a deeper pavilion than a round brilliant. Light entering the top travels further before it comes back out. A longer path through the material means more chance for the faint yellow in a lower colour grade to tint what you see. Broad facets also present that colour in larger continuous areas rather than breaking it up.
That is why our colour advice for cushions runs one or two grades tighter than it would for a round. Here is what we tell people at the counter.
| Stone size | White metal setting | Yellow or rose gold setting |
|---|---|---|
| Under 1.00 carat | H or better | I or J is fine |
| 1.00 to 1.49 carat | G or better | H or I |
| 1.50 carat and up | F or G | G or H |
The metal does real work here. A warm yellow gold prong reflects into the stone from the edges, so a faint tint in the diamond stops reading as a fault and starts reading as part of the design. Set the same stone in platinum next to a cold white metal and the tint becomes obvious. If you are weighing those metals, our platinum against white gold comparison goes through cost, colour and maintenance.
Spread: why a cushion looks smaller per carat
Carat is a measure of weight. Two stones of identical weight can show different amounts of surface when you look down at them, and the cushion is on the smaller end of that scale.
GIA says it for cushions directly: their deeper proportions can make them appear smaller than other shapes of the same carat weight, but they often come at a lower price per carat compared to round brilliants.
The deep pavilion is the cause. It is inherited straight from the old mine cut, and it stores weight beneath the girdle where nobody can see it from above. A shallower stone of the same weight spreads that material outward instead, giving a wider face.
The practical answer is to stop shopping by carat and start shopping by millimetres. Ask for the length and width of each stone, write the numbers down, and compare those. A cushion that measures 6.50 by 6.50 millimetres looks the same size on a hand whether the report says 1.05 carats or 1.15. Our post on why same-carat diamonds look different works through this, and which diamond shapes look bigger per carat ranks the shapes.
The price side of that GIA quote is worth holding onto. A cushion typically costs less per carat than a round, so part of the spread you lose comes back as budget you can spend on colour or on a wider band.
There is no cut grade to hide behind
With a round brilliant you can lean on the cut grade printed on the report. With a cushion you cannot, because there is no such grade.
GIA's fancy shape guide states that while GIA does not grade the overall proportions of fancy cut diamonds, a GIA Diamond Grading Report does contain an assessment of the diamond's Finish, which includes Polish and Symmetry. Its oval guide puts the same rule the other way around: GIA only assigns an overall cut grade to round brilliant diamonds, since their standardized shape allows for consistent evaluation.
So a cushion report gives you polish, symmetry, measurements, a description of the shape and cutting style, and a proportion diagram. Judging whether the stone is beautifully cut falls to you.
Three checks we run on every cushion that comes through the shop, and that you can run yourself in any decent light.
Look for a dark centre. Tilt the stone until it is flat, face-up, at arm's length. A stone cut too deep shows a dull grey patch under the table that does not light up as you move. Move on from that one.
Check the corners are even. Turn the stone slowly. The four corners should curve the same amount. One tight corner and one lazy one is a symmetry problem you will notice every day once you have seen it.
Watch it in ordinary light. Jewellery shop spotlights make almost anything sparkle. Step toward a window, or into the shade of a doorway, and see what the stone does with soft light. That is the light it lives in.
Compare the cushion against its neighbours while you are at it. Our guides to emerald cut diamonds and princess cut diamonds cover the two shapes buyers most often weigh against a cushion, and our diamond overview page covers the four Cs from the start.
Setting a cushion so it lasts
The rounded corners of a cushion are kinder than the sharp points of a princess cut, and the corner is still the part that takes the knock. Diamond resists scratching better than anything else you will wear, and a corner can still chip under a direct hit on a door frame.
Our bench sets cushions three ways. Four corner prongs that reach around the curve, which is the traditional choice and shows the most stone. Double prongs on each corner for someone who is hard on rings. A full bezel, a rim of metal around the whole girdle, for nurses, cooks, climbers and anybody who told us their ring takes a beating.
Whichever you choose, look at the prongs once a year. Our guide to loose stone warning signs covers the rattle test you can do at home in ten seconds.
Engagement rings from our cases
A few rings from the shop, including settings that take a cushion well. Bring in a stone and we will show you how it sits in each.
Key Takeaways
- The cushion descends from the old mine cut, which GIA dates to the 1700s and calls the most common cut until the late 19th century, with a squarish shape, high crown, small table, deep pavilion and large culet.
- Two facet patterns share the name. GIA describes brilliant cushions as having larger facets with a softer sparkle, and modified cushions as adding extra facets that create a crushed ice effect. Check the cutting style line on the report.
- Ratios near 1.00 to 1.05 read as square, 1.10 to 1.20 as a soft rectangle, and above 1.20 as an elongated cushion. GIA publishes suggested ratios for oval, marquise, pear and heart, and leaves cushion off the list.
- Broad facets and a deep pavilion let body colour show more than in a round, so we set our floor at H or better under 1.00 carat in white metal and move to F or G above 1.50 carat.
- GIA gives no overall cut grade to fancy shapes, only polish, symmetry, measurements and a proportion diagram, so judge the stone yourself in ordinary light and shop by millimetre measurements rather than carat.
Frequently Asked Questions
What is the difference between a cushion brilliant and a cushion modified brilliant?
It is the facet pattern, and it changes how the stone looks from across a room. GIA describes the split plainly: brilliant cushions have larger facets that emphasize clarity with a softer sparkle, while modified cushions include extra facets that maximize brilliance and create a crushed ice effect. The extra facets sit as a further row on the pavilion, the cone-shaped bottom half of the stone. A standard cushion brilliant throws broad flashes you can count with your eye. A modified one scatters the same light into many small glints that shift as you move. Neither is better made. They are two products that happen to share one word on a price tag. Ask which one you are looking at before you compare prices between two stones, because you are otherwise comparing two different appearances.
How do I tell a crushed ice cushion from a chunky one in the shop?
Hold the stone under a single light source, arm's length from your eye, and watch the face-up pattern as you tilt it. A chunky cushion brilliant shows a small number of large dark and bright blocks that switch on and off as the angle changes. You can pick out individual facets. A crushed ice cushion shows a shimmer with no blocks you can name, like light on moving water. The second test is the grading report. GIA prints the cutting style, and the words cushion modified brilliant tell you there are extra facets on the crown or pavilion. If the report says cushion brilliant with no modifier, you are holding the chunky pattern. Do both checks. The report tells you what it is, and your eye tells you whether you like it.
Where does the cushion cut come from?
It is one of the oldest shapes still in production. GIA calls the cushion one of the oldest diamond shapes and cutting styles, and traces it to the old mine cut, which dates back to the 1700s and was the most common cut until the late 19th century. The old mine cut has a squarish outline with a high crown, a small table, a deep pavilion and a large culet, which is the flat facet at the bottom tip. The name came later. GIA explains that the term came into common use in the late 1800s, when diamond production from Africa began to eclipse production from the old mines of Brazil. So a cushion today is a descendant of a cut named for Brazilian mines that new African finds had made old.
Does a cushion show more colour than a round diamond?
Yes, in our experience at the bench, and the reason is geometry. A cushion has broader facets and a deeper pavilion than a round brilliant. Light takes a longer path through the stone before it leaves, and body colour has more material to tint on the way. That is a physical description rather than a graded number, because GIA grades colour the same way for every shape, face-down against a master set. What changes is how much of that colour you see face-up on a finished ring. Our practical guidance: if you want a white-looking cushion, we suggest staying at H or better, and we push toward G or F once you pass 1.50 carats, because a bigger stone means a longer light path. If you are setting in yellow or rose gold, the metal warms the stone anyway and I or J can look right.
Which length-to-width ratio should I choose for a cushion?
It depends on the look you want, and this is one of the few places where the number is a taste setting rather than a quality setting. A ratio near 1.00 to 1.05 reads as a square cushion, the classic antique look with four even sides. From 1.10 to 1.20 the eye starts to read it as a soft rectangle. Past 1.20 it becomes a clearly elongated cushion that flatters a shorter finger and sits closer to a radiant in feeling. GIA publishes suggested ratios for several fancy shapes in its fancy shape buying guide, listing oval at 1.33 to 1.66 to 1 and pear at 1.50 to 1.75 to 1, with cushion left out. Measure the stone loose, then look at it on the hand it will live on. The hand decides.
Why does a cushion look smaller than a round of the same carat weight?
Carat is weight, and weight can be carried where you cannot see it. GIA puts it directly for cushions: their deeper proportions can make them appear smaller than other shapes of the same carat weight, but they often come at a lower price per carat compared to round brilliants. The deep pavilion inherited from the old mine cut holds weight below the girdle, where nobody looking down at the ring can see it. So a 1.00 carat cushion usually shows less face-up surface than a 1.00 carat round. The fix is to shop by millimetre measurement rather than by carat. Ask for the length and width in millimetres, write them down, and compare stones on those numbers. We wrote more on this in our guide to why two diamonds of the same carat can look different sizes.
What clarity grade do I need in a cushion?
It depends on which facet pattern you buy, which is why the two questions belong together. A crushed ice cushion breaks the face-up view into many small glints, and that busy pattern makes a small inclusion hard for the eye to find. A chunky cushion brilliant has large open facets that act like little windows, and an inclusion sitting under one of them can be visible without magnification. Our shop rule: on a crushed ice cushion, SI1 is often clean to the naked eye and worth the saving. On a chunky cushion brilliant, we start at VS2 and we look at the plot on the report to check where the inclusions sit. An inclusion under the table is the one that shows. An inclusion near the girdle can often be hidden by a prong. Always look at the actual stone before you decide.
Does GIA give cushion cut diamonds a cut grade?
No. GIA states in its fancy shape buying guide that while GIA does not grade the overall proportions of fancy cut diamonds, a GIA Diamond Grading Report does contain an assessment of the diamond's Finish, which includes Polish and Symmetry. The same point appears on GIA's oval cut guide, which says GIA only assigns an overall cut grade to round brilliant diamonds, since their standardized shape allows for consistent evaluation. So there is no overall cut rating to lean on with a cushion, the way a round brilliant carries one. You get polish, symmetry, measurements, a description of shape and cutting style, and a proportion diagram. Judging the cut is your job, done with your own eyes on the actual stone under ordinary light.
Is a cushion cut a good choice for an engagement ring worn every day?
We think so, and the corners are the reason. A cushion has rounded or soft corners rather than the sharp points of a princess cut, so there is less of a thin edge exposed to knocks against door frames and countertops. Diamond is hard, and hardness describes resistance to scratching. A sharp corner can still chip under a direct hit, because chipping is a different property. Rounded corners spread that risk. The setting matters as much as the shape. We use four corner prongs that reach over the curve, or a bezel for people who work with their hands. Check the prongs once a year. Our guide to the warning signs of a loose stone shows what to listen and look for between visits, and our bezel against prong comparison covers the trade-offs.
Sources
- GIA 4Cs: Cushion Cut Diamond, An Old And New Classic
- GIA 4Cs: Guide to Old Mine Cut Diamonds
- GIA 4Cs: Guide to Diamond Engagement Ring Shapes
- GIA 4Cs: Expert Tips for Buying Fancy Shaped Diamonds
- GIA 4Cs: Oval Cut Diamond Guide
Data sourced September 2026. Facet patterns, historical dates and grading report contents are quoted from GIA's published guides as they stood at that date. Colour grade recommendations, setting advice and the shopping checks are our own practice at the Coquitlam bench and are offered as opinion. If GIA updates a position, tell us and we will correct this page.
Visit Vanhess
We are a family-run studio at 2929 Barnet Highway in Coquitlam, and we designed and made most of what sits in our cases. Bring in a cushion you are considering, or a stone you already own, and we will put it under the loupe beside a chunky one and a crushed ice one so you can see the difference with your own eyes before you spend anything. We serve Coquitlam, Port Moody, Burnaby, New Westminster and Vancouver. Call us at +1 (604) 653-6449.
