A square cushion is what happens when a square is allowed to soften. This 1.00 carat lab grown diamond measures 5.90 x 5.76 mm, square to within 0.14 mm, with the corners rounded into the outline and the interior broken into the small tumbling facets that give cushions their crushed-ice sparkle. IGI report LG643449098 grades it D color and VS 1 clarity with excellent polish and excellent symmetry. It is listed unset with our loose lab grown diamonds, ready to be built into a ring.
1.00 Carat
D Color
VS 1 Clarity
Square Cushion Brilliant
IGI Certified
Excellent Polish & Symmetry
Square, with the corners taken off
Cushion is a shape named after a pillow, and this is the square version of it rather than the elongated one. The measurements are 5.90 x 5.76 x 3.86 mm, a length-to-width ratio of 1.02:1, which is square to the eye and very nearly square on paper: 0.14 mm separates the two directions.
What separates it from a princess cut is those corners. A princess keeps them sharp at ninety degrees; a cushion rounds them into the outline, which softens the whole silhouette and removes the four most vulnerable spots on the stone at the same time. It is why cushions read as antique where princess cuts read as modern, and why a cushion drops so comfortably into a bezel or a low-profile setting.
It is also the deep one. The 3.86 mm depth is about 67 percent of the 5.76 mm width, and that depth is where a cushion keeps its light. Cushion brilliant faceting scatters light into many small flashes instead of a few broad ones — the effect the trade calls crushed ice. It reads as glitter rather than strobe, it performs unusually well in candlelight and dim rooms, and it is forgiving of small inclusions because there is no large open facet for the eye to settle on. The cushion cut engagement rings collection shows the difference against a step-cut outline, and our guide to ring styles and setting types places the shape among the alternatives.
What the grades on report LG643449098 mean
D color is the colorless end of the scale with no grade above it. On a crushed-ice stone that counts for more than it sounds: hundreds of small facets each return a little light, so any body color present gets multiplied across all of them rather than concentrated in one broad table.
VS 1 means very slightly included, the grade at which inclusions are hard for a grader to find at 10x magnification and invisible to the unaided eye. Paired with the cushion’s busy faceting, it is about as clean as the shape can be made to look. Fluorescence is graded None, so the stone behaves identically in daylight and under UV.
Polish and symmetry are both Excellent, describing the finish of the facets and the accuracy of their alignment. The report states no overall cut grade, which is standard for fancy shapes, so the finish grades and the measurements are what you read in its place. The 4Cs guide works through the scales, and the lab grown diamond price guide explains which of the four actually moves the number on the tag.
Settings that suit a square cushion
A square outline centers easily, which makes the cushion one of the more forgiving shapes to design around. Four prongs set compass-style at the corners is the cleanest treatment and leaves the whole outline visible. A bezel follows the rounded corners without any special accommodation, because there are no points to protect.
Halos are where cushions have always looked their best. A ring of small stones repeating the soft square amplifies the outline and pushes the apparent size up considerably, and vintage detailing such as milgrain edges or pave shoulders suits the shape for the same reason: it already reads as an heirloom cut even when the stone is new. Look through the halo engagement rings for the classic route, or custom engagement rings if you want the setting drawn around these specific measurements.
Buying the diamond loose means the setting decision comes second, made with the exact dimensions already in hand. You can begin at design your own engagement ring.
Where this diamond came from
IGI’s comments record that the stone was created by Chemical Vapor Deposition. CVD growth starts with a thin diamond seed in a sealed chamber of carbon-rich gas; energy breaks the gas down and carbon settles onto the seed atom by atom, building a single crystal upward over several weeks. What comes out is diamond by every physical and chemical measure, and how lab grown diamonds are made covers the process properly.
Because there is no mine involved, sourcing is simple to state: the stone is conflict-free by origin, with a production record behind it rather than a supply chain to audit. If you are still choosing between grown and mined, lab grown vs natural diamond lays out the trade-offs on price, grading and resale without a sales pitch attached.
Everything below comes from IGI report LG643449098; the ratio and depth percentage are calculated from the measurements on that report and nothing else is stated. Diamond is April’s birthstone, so a certified loose stone works as a birthday commission as readily as an engagement one — see April birthstone jewelry.
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Stone Laboratory grown diamond
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Shape and cut Square cushion brilliant
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Carat weight 1.00 carat
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Measurements 5.90 x 5.76 x 3.86 mm
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Length to width 1.02:1 (calculated from the measurements)
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Depth 3.86 mm, about 67% of the 5.76 mm width
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Color grade D
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Clarity grade VS 1
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Cut grade Not stated on this report
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Polish Excellent
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Symmetry Excellent
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Fluorescence None
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Growth method Chemical Vapor Deposition (CVD)
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Inscription IGI LG643449098, laser-inscribed on the girdle
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Report IGI LG643449098, issued July 16, 2024
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Birthstone April
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Custom setting Available
Certification & care
The diamond ships with IGI report LG643449098, issued July 16, 2024. The report number is laser-inscribed on the girdle, so stone and paperwork stay tied together for as long as you own it, and you can pull the same grading record yourself through IGI’s online report check rather than relying on this page. If you want to know how IGI’s grading compares with the other major laboratory, IGI vs GIA certification covers it.
The measurements to work from are 5.90 x 5.76 x 3.86 mm. The 0.14 mm difference between the two directions is invisible to the eye but real on a bench, so hand the report to whoever makes the setting before any metal is cut. The depth is the number that surprises people: at 3.86 mm this is a deep stone, which affects how high it will sit in a low setting.
Diamond is Mohs 10 and nothing in ordinary handling will scratch it, but a loose stone still needs keeping. Store it in its own box rather than loose with other jewelry, which it will happily scratch. Warm water, a drop of mild dish soap and a soft brush lifts the skin oil off the pavilion that makes a cushion look flat, and a lint-free cloth finishes it. Once it is set, our guide to caring for an engagement ring takes over.
Square cushion lab grown diamond questions
Is a lab grown diamond a real diamond?
It is. Chemically, physically and optically this is diamond — the same carbon lattice, the same Mohs 10 hardness, graded on the same color and clarity scales any other diamond is graded on. It is not a simulant and not an imitation; the only thing that differs is the place the crystal formed. Our article on whether lab grown diamonds are real diamonds sets out the evidence.
What is a square cushion brilliant, and how is it different from a princess cut?
A cushion is a squared outline with the corners rounded off and brilliant-style faceting inside. A princess cut keeps its corners sharp at ninety degrees. Both are square in silhouette, but the cushion’s soft corners give it an antique character and remove the four points that a princess needs prongs to protect. The faceting differs too: a princess is more geometric, a cushion more scattered.
Is this stone actually square?
Effectively, yes. It measures 5.90 x 5.76 mm, a length-to-width ratio of 1.02:1. The 0.14 mm difference is well below what an eye can resolve on a stone this size, so it reads as square in any setting, but it is worth knowing about when the head is being made.
What does crushed-ice sparkle mean?
It describes the way cushion faceting breaks light into a lot of small flashes rather than a few large ones, so the stone looks like a heap of broken ice catching light from every direction. It reads as glitter rather than as flash. Some people prefer the broad, defined flashes of a step cut; crushed ice is livelier, hides inclusions better and performs well in low light.
How white is D color?
D is the top of the color scale with nothing above it, meaning no detectable body color at all. It matters more than usual on a crushed-ice stone, where hundreds of small facets would each return a hint of any tint present. Fluorescence is graded None on this report, so the stone does not shift under UV either.
Will I see the VS 1 inclusions?
No. VS 1 means very slightly included: a trained grader has to work to find the characteristics at 10x magnification, and they are not visible to the unaided eye. The cushion’s busy faceting makes them even harder to spot than they would be in a step cut.
Why does the report not give a cut grade?
Overall cut grades are assigned to round brilliants only. Fancy shapes, cushions included, are not graded that way, so the report gives polish and symmetry — both Excellent here — along with the full measurements, and leaves the proportions for you to read. We are not going to state a cut grade that IGI did not issue.
What is the laser inscription, and can I check the report myself?
The girdle is inscribed IGI LG643449098, which is the report number. It is microscopic and needs magnification to read, and it is what lets any jeweler confirm the stone in the setting is the stone on the certificate. You can enter the same number on IGI’s online report check to see the grading record independently of us.
Does carat weight tell me how large the stone will look?
Only partly. Carat is weight, one fifth of a gram, while millimeters describe what you actually see. A cushion this deep carries some of its weight below the girdle, which is normal for the shape and part of how it holds light. Read the 5.90 x 5.76 mm face-up measurements alongside the 1.00 carat figure rather than instead of it.
Can this diamond be set into a ring, and who does the work?
Yes, and we do it. Aquamarise builds custom rings around loose stones, so this cushion can go into a design of your choosing, with the setting and the final band sizing handled together on the bench — that is a jeweler’s job, not a separate errand for you. Begin at build your custom ring and quote the report number.
Will it test as a diamond?
Yes. Handheld testers measure thermal conductivity, and a grown diamond conducts heat exactly as a mined one does, because it is the same material. Separating grown from mined takes specialist laboratory instruments, which is exactly why this stone carries an inscription and a report.
Is a lab grown diamond conflict-free?
Yes, by origin. There is no mine in the chain at all, so the stone comes with a production record rather than a sourcing question. Our piece on what makes jewelry ethical goes further into how we assess materials.
How do I clean and store a loose diamond?
Warm water, a drop of mild dish soap and a soft brush, then a lint-free cloth. What dulls a loose stone is skin oil on the pavilion, and it comes away in seconds. Store it in the box it arrives in rather than loose with other pieces, because at Mohs 10 this diamond will scratch every one of them.
How does it ship, and what is the return policy?
Loose stones ship free within the USA, insured and tracked, with the IGI report enclosed. The return terms that apply to a loose stone are set out in full on our returns and refunds page, and they are worth reading before you order if you plan to have the diamond set.
