Collection: Radiant Cut Diamonds

A radiant is a square or rectangular diamond with cut corners and full brilliant faceting throughout. It was created in the 1970s to combine the clean outline of an emerald cut with the sparkle of a round — a step-cut silhouette with brilliant-cut light behaviour underneath. It is the only shape designed from the outset to do both.

Both, and the difference is significant. A square radiant sits around 1.00 to 1.05 and reads as bold and compact. A rectangular radiant runs from about 1.15 to 1.35 and elongates the finger the way an oval does — it is the more requested of the two at the moment, particularly around 1.20 to 1.30. Some are cut longer again for real drama.

The outline is on the certificate as length-to-width ratio, but it is a shape where you should see two or three before deciding.

Yes — radiant is the shape most closely associated with fancy coloured diamonds, and especially with fancy yellow.

The reason is the faceting. Those brilliant facets reflect light back and forth through the stone repeatedly before it reaches your eye, and every pass deepens the apparent colour. A yellow diamond cut as a radiant will face up noticeably richer than the same rough cut as an emerald cut, where the open step facets let light straight through and wash the colour out.

That is why the great majority of fancy yellow diamonds are cut as radiants or cushions rather than step cuts — the cutter is choosing the shape that gets the most colour out of the crystal. If you are looking at fancy colour, radiant is where to start. View our fancy colour diamonds.

The corners. A princess has sharp uncut corners and a crisp, geometric outline; a radiant has trimmed corners, which softens the silhouette and makes it considerably more robust. A radiant is also usually cut with more brilliance and depth of sparkle. If you want the sharpest possible square, princess. If you want a square with softer edges and no corner anxiety, radiant.

Outline aside, everything. They can look similar from a distance — same rectangular shape, same cut corners — but an emerald cut is a step cut with long open facets and broad mirrored flashes, while a radiant is a brilliant with fragmented, lively sparkle. Emerald is restrained; radiant is bright. Worth seeing side by side, because people often arrive wanting one and leave with the other.

The geometry does the work, so the settings that suit it best are the ones that frame the outline rather than compete with it.

Three stone is the classic. A radiant centre with a matched pair either side — tapered baguettes for a clean architectural line, trilliants for something bolder, or round brilliants if you want the contrast. Set as a matched trio of radiants it reads as very deliberate and modern.

Halo suits it particularly well. A surround of round brilliants against a radiant centre sets up a lovely contrast — the soft scattered sparkle of the small rounds against the crisp rectangular outline of the centre stone. The halo also visibly enlarges the stone, so a radiant that sits just under the size you wanted can be framed up to look considerably bigger.

Side stones run diamonds along the shoulders and lead the eye into the centre stone. Tapered baguettes suit a radiant especially well, since the straight lines pick up the geometry of the cut corners.

Solitaire works if you want the shape to speak for itself, and a four-claw setting is enough since the cut corners do not need protecting.

All made to order in our own workshop, built around your stone.

Because there is no cut grade to fall back on. GIA assigns a formal cut grade only to round brilliants, so on a fancy shape the certificate tells you polish and symmetry and little else about how the stone actually performs. Symmetry becomes the closest thing you have to a proxy.

But there are two kinds, and the certificate only covers one. The graded symmetry measures facet alignment under magnification. What you actually see is outline symmetry — whether the two halves mirror each other. A pear with shoulders of different heights, an oval with one end fuller than the other, a marquise with points that do not line up: none of that necessarily drops the grade, and all of it is obvious once the stone is on your finger.

Asymmetry also affects light. Facets that do not align properly send light out the side instead of back to your eye, which is what causes dead patches and heavy bowties.

So on a fancy shape, look for Very Good or better on the certificate — then look at the stone. The outline either reads as balanced or it does not, and that judgement is one you can make yourself in a few seconds.

This is a shape where you can be relaxed. The brilliant faceting disguises body colour well, so H or even I often faces up perfectly white — a grade or two lower than you would want in an emerald cut of the same size. That is a real saving, and it is one of the reasons radiants represent good value.

Rarely. The busy faceting is very effective at masking them, so SI1 is frequently eye-clean and SI2 is worth looking at. Radiant is one of the more forgiving shapes on clarity, which is another place the budget stretches. We check every stone face-up before recommending it.

A square radiant is roughly 5.7 x 5.7mm; a rectangular one around 6.5 x 5.0mm. Radiants are often cut deep, so like cushions they can face up slightly smaller than the carat suggests — worth checking the measurements rather than the weight.

Because our images and videos are taken at high magnification — far closer than any human eye gets to a diamond, and far closer than the standard the stone was graded to.

Clarity grading is done under 10x magnification. That is the international standard: a grader with a 10x loupe decides whether an inclusion is there and how it affects the grade. Online photography routinely runs at twenty, thirty times life size or more, so you are seeing the stone at several times the magnification GIA used to grade it. An inclusion that fills your screen may be something the grader needed a loupe to find at all.

Colour matters too. A white or transparent inclusion — a feather, a cloud, a crystal without body colour — is far harder to see than a dark carbon spot of the same size, because there is little contrast against the diamond around it. Two stones can carry the same grade and look entirely different in the hand for that reason alone.

We photograph at high magnification deliberately. We would rather show you everything than shoot a diamond flatteringly and have you surprised later. But an inclusion that looks obvious on screen is very often invisible in the hand, at arm's length, on a moving finger, in ordinary light.

The grade tells you what is there. The magnification tells you where. Neither tells you whether you would ever notice it — that is a judgement we make face-up, under proper light, on every stone we hold.

Considerably, and it is worth knowing before you compare stones in different places.

Jewellery displays are lit to sell. Rows of halogen or bright LED spots directly above the case flood the stone with intense, concentrated light from every angle. That produces maximum sparkle and, at the same time, washes out inclusions — the scintillation is so busy that small imperfections simply disappear into it. A diamond in a well-lit display case is showing you close to the best it will ever look.

Daylight is the opposite. Soft, diffuse, coming from one direction. Sparkle is quieter, and anything inside the stone has nowhere to hide. Diamond grading uses controlled, colour-balanced daylight-equivalent lighting for exactly that reason — it is neutral, and it is reproducible.

Neither light is dishonest. But if you look at a stone under spotlights and then take it outside, you will see a different diamond, and most of a ring's life is spent in ordinary light.

When you view diamonds with us, you see them under professional diamond grading lights — the same neutral, colour-balanced lighting the laboratories use — and in natural daylight. No spotlit display case. If a stone looks right under those conditions, it will look right anywhere.

Always, and we would insist on it.

A single diamond on its own looks excellent. There is nothing to measure it against, so your eye accepts it. Put a second stone beside it and differences appear immediately that you would never have seen alone — one reads slightly warmer, one has more life, one throws broader flashes while the other glitters more finely.

This is how the trade buys, and it is the only reliable way to judge colour in particular. Colour grading is comparative by definition: graders work against a set of masterstones, not from memory. Your eye works the same way. Two stones a grade apart are obvious side by side and almost impossible to separate one at a time.

So we will put several in front of you. Sometimes that means you choose a lower grade than you came in for because you genuinely prefer how it looks, and sometimes it means you spend a little more because you can finally see the difference. Either way you will know why, which is the point.

No. Every diamond we sell is a natural diamond, and we've never dealt in lab-grown, simulants or treated stones.

A lab-grown stone is a manufactured product. It's grown in a reactor over a few weeks, then mass produced in unlimited quantities in any size or grade. That's the fundamental difference: a natural diamond took billions of years to form and exists in finite supply, while a laboratory-grown one is a commodity with no ceiling on production. It shows in the pricing — as capacity has scaled, lab-grown prices have fallen steeply and continue to fall, and there is no established secondary market for them.

What you're buying with a natural diamond is scarcity and origin. Rare, and natural. It's why we've never sold anything else. Read our full comparison of natural and lab-grown diamonds.

Our diamonds are independently certified, most commonly by GIA, with others graded by DCLA or HRD. The certificate is issued by the laboratory, not by us, and it accompanies the stone when it ships.

Yes. We are in Sydney's CBD and we see clients by appointment, so you can view stones side by side and compare them in person before deciding.

Just ask us. Finding a particular stone is a large part of what we do, and there's no obligation when you enquire. We'll do our best to source the finest quality natural diamond for you.

Our list is smaller than you'll see on some sites, and that's deliberate. Every diamond here is one we've looked at properly before listing it. Many diamond websites show tens or hundreds of thousands of stones drawn from shared trade lists — diamonds held elsewhere that the seller hasn't seen and won't see unless you order one. It looks like more choice, but nobody has assessed the individual stone, and two diamonds with the same details on paper can look quite different.

So if what you want isn't here, tell us what you're after and what you'd like to spend. We'll look for it, check anything we find ourselves, and only show you stones we'd be happy to recommend. If we can't find the right thing at your budget, we'll say so and talk through the options — sometimes a small change in colour, clarity or size makes all the difference.

Either way, you'll only ever be offered a diamond that we have complete confidence in recommending to you, and it will not just be based on the cheapest price.

Yes. Most clients select the diamond first and then the setting — either one of our existing designs or a fully custom piece made to your description or an image. Everything is handmade by our own jewellers.

Yes. We have many loyal customers all over Australia, and we're able to consult by phone and share photos and videos whenever possible.

Distance is not the obstacle people expect. We'll guide you through the options and select the finest quality diamonds and gemstones for you, so you can make an informed decision from wherever you are. The same applies to custom made engagement rings and jewellery — we'll talk you through it and keep you across it as it's made.

We deliver fully insured anywhere in Australia — every capital city, and regional and rural addresses just the same.

If you are able to come in, we'd always rather show you the stones in person — and if you're travelling to Sydney, appointments can be arranged on weekends.

Tell us the number you have in mind and what matters most to you, and we will show you the best stones we hold at that level. Radiant is a shape where dropping a colour or clarity grade often costs you nothing visible, so the budget goes further than most people expect. We are a diamond merchant, not a retail jeweller — we do not charge retail prices, and we source natural certified diamonds to suit your budget. Diamond Imports is a foundation member of the Diamond Dealers Club of Australia, and you will deal directly with Daniel throughout.