The Ultimate Guide to Radiant Cut Diamonds

concentric radiant cut facet structure

Radiating concentric rings seen in a radiant cut diamond.

The radiant cut can be thought of as a hybrid which combines advantages of the three most popular diamond shapes. It has the fire and brilliance of the round cut brilliant, the clipped corners of the wonderful Asscher cut and the “openness” of the emerald cut.

With a unique embodiment of different traits, it appeals to people who are looking for a modern-fusion look in their engagement rings. If you are shopping for a radiant cut diamond engagement ring, you have come to the right place.

In this article, I’m going to show you how to pick a beautiful radiant cut diamond and reveal the insider tips that will help you save money. You will find out exactly what to look out for and to avoid when shopping for one.

Let’s jump right in…

Recommended Proportions For Radiant Cut Diamonds

Unlike the round brilliant diamond, the GIA report does not list a cut grade for a radiant cut diamond. This is because radiant diamonds have many non-standardized facet structures and there can be a wide range of proportions they can be cut to.

Due to the lack of cut information provided by a lab report, it is much harder for an inexperienced shopper to pick out a radiant cut with strong light return. Also, it doesn’t help that the majority of diamonds in the market are poorly cut.

With that said, I’ve compiled a table of ideal proportions that is designed to help you quickly weed out poorly cut diamonds. You may want to use the proportions as a general guideline to start your search when shopping for a diamond.

Excellent Very Good Good Fair/Poor
Table % 60% – 66% 58% – 69% 57% – 72% Outside Ranges
Depth % 59% – 65% 57% – 67% 56% – 70% Outside Ranges
Polish/Symmetry Excellent – Very Good Good Outside Ranges
Length to Width 1.00 – 1.20 1.21 – 1.25 1.26 – 1.35 Outside Ranges
Girdle Thickness Thin – Thick V. Thin –  V. Thick Outside Ranges
Culet Size None Very Small Small Outside Ranges

Note: The table of ideal proportions should only be used as a reference for filtering and narrowing down your selections.

With fancy cut diamonds, numbers cannot be used to determine or guarantee light performance by themselves. When buying radiants, you will need to consider photography/videography data and include ASET analysis as part of your decision making process.

To help you visualize how a well cut radiant diamond looks like, check out these 2 examples below that are handpicked for their superb brilliance and scintillation patterning. Hopefully, this gives you a better idea of the traits to look out for.

well cut radiant concentric cone pattern diamond
white light sparkle scintillation radiant diamond brilliant cut

James Allen and Blue Nile are recommended vendors who stock huge selections of GIA certified radiant cut diamonds. Their 360° videos create an intuitive shopping experience that enables you to see exactly what you are buying.

Avoid the Dreaded Bow Tie Effect in a Radiant Diamond

When radiant cut diamonds are polished to poor proportions, it can give rise to issues like dark looking bow-ties. As the name suggests, the bowtie resembles the shape of a man’s bow-tie and it creates ugly looking patches across the diamond’s body.

These dark looking areas are caused by misaligned facets that create light obstruction when a viewer sees the diamond. Below are 2 examples of radiant diamonds with bowtie issues that you want to avoid.

splintery ugly black triangle areas in gia radiant cut diamond
radiant cut diamond squarish bowtie dark black areas

Radiant cut diamonds with ugly bowties that you should avoid.

Here, I want to point out that the GIA grading report makes no mention of the presence of bowties and you need to see the diamond to assess it yourself. This is another reason why I always emphasize the need to utilize videos in unbiased lighting environment when selecting a radiant diamond.

Recommended Color Ratings for Radiant Cut Diamonds

gia color chart d to k comparison of radiant cut diamonds

GIA color comparison chart of D to K ratings.

Radiant cut diamonds generally have lesser brilliance and sparkle compared to round diamonds due to their cutting style. As a result, radiant cut diamonds tend to reveal their body color more readily.

If you are looking for an icy white color appearance, I recommend a G or better color grade. For larger carat size diamonds above 2ct, you would probably need an F color grade to ensure a white appearance.

On the other hand, if you prefer a yellow gold setting or vintage looking appearance, going down to lower color ratings would be perfectly fine. The warm tint exhibited by the diamond can actually help complement the style of the ring you are looking for.

While I personally prefer a white looking diamond, evaluating color in radiant cut diamonds is subjective. At the end of the day, you should choose a color grade that your recipient prefers.

What is the Best Clarity Rating to Buy for a Radiant Diamond?

When it comes to clarity, the radiant cut diamond is not good at concealing inclusions because of their large table facet and generally poor light return. Speaking broadly, you would typically require a VS2 or better clarity grade to get an eyeclean diamond.

The caveat is that you must always use a magnified video taken under unbiased lighting conditions to help you evaluate eyecleanliness. As the examples below show, the inclusions found in VS2 diamonds can be vastly different and it is no guarantee of an eyeclean diamond.

e vs2 radiant cut not eyeclean diamond 1 carat
eyeclean yellowish tint 1 carat vs2 radiant cut diamond

Can you tell which is the eyeclean diamond between these 2 examples?

Also, depending on the carat size of the diamond you are getting, you may require a higher clarity rating (for large sized diamonds) or may even go lower to SI1 clarity at smaller carat sizes to save costs.

Pro tip: Due to the limited selections available for radiant cut diamonds, you should also keep an open mind about buying higher clarity grades and focus on getting a well cut diamond instead.

2 Types of Radiant Cut Diamonds: Rectangular & Squarish

Radiant cut diamonds are traditionally cut to rectangular outlines but there are also some cutting styles which result in square looking outlines. Very often, people confuse square cut radiant diamonds with the cushion cut because of their squarish outlines.

However, you can tell them apart by looking at their corners. Radiant cut diamonds have straight cut corners while cushion cut diamonds have curved corners which gives them more of a contemporary feel.

This is also the reason why radiant cut diamonds are technically classified as “cut corner rectangular modified brilliant” or “cut corner square modified brilliant” by the GIA. Basically, you can think of radiant cut diamonds as princess cut diamonds with their 4 corners cut off.

square radiant cut diamond

Square radiant cut

rectangle radiant cut diamond

Rectangle radiant cut


So what’s the difference between a square and a rectangle radiant cut diamond? In terms of optical properties, a radiant diamond that is more squarish typically has better brilliance and sparkle factor.

On the other hand, an elongated stone is known to have more of a fiery presence and a better spread of light scintillation.

Ideal Length to Width Ratio for Radiant Cut Diamonds

The length to width ratio of a radiant cut diamond will determine its outline and shape appeal. My personal preference lies with the range of 1.15-1.25 where the diamond takes on a slightly rectangular outline.

This is the range where the facet structure works best to bring out the concentric appearance and traditional flavor of a radiant cut stone. For a quick and easy reference, here’s a chart that depicts how radiant cuts with different length to width ratios would look like.

radiant cut diamonds length to width ratio

Do note that there are diverse preferences when it comes to shape appeal in radiant cut diamonds. If you aren’t sure, you may want to review diamonds with different length to width ratios to find out your preferences.

Some people may prefer a perfectly square 1:1 ratio and that’s perfectly fine. Some people like elongated shapes which derails from a traditional appearance.

Personally speaking, if I wanted to buy a square shaped or elongated diamond, I would rather purchase a princess cut or marquise instead of a radiant diamond.

How Much Does a Radiant Cut Diamond Cost?

Compared to round diamonds, the prices of radiant cut diamonds are generally 25-30% lower per carat weight. This means that you can get a larger sized diamond for less money if you are on a budget.

Depending on the specifications of the 4Cs, prices can be drastically different. Below, I’ve compiled a price comparison table of 1 carat sized radiant cut diamonds as a reference.

1 carat radiant cut diamond price comparison gia certified

Price comparison of GIA certified 1ct radiant cut diamonds.

As you can see, the cost of a 1ct radiant cut diamond can range anywhere between $2,000 to $8,000. A diamond with the best of the best material specifications of D/FL (~$7,500) costs nearly 3 times as much as another diamond with lower clarity/color ratings.

But here’s the thing, a more expensive diamond doesn’t necessarily mean it will look better or have better sparkle. Diamonds with higher color and clarity ratings are more expensive because of rarity factors.

In fact, you don’t need a D/IF grade for a great looking diamond when a well-cut G/VS2 can look completely identical in the face up view. If you are a practical person or don’t need a D/IF symbolic grade, you can save yourself a tidy sum of money by choosing a lower color/clarity diamond.

Best Setting Designs For Radiant Cut Diamond Engagement Rings

Radiant cut diamonds can make for a great solitaire ring that shows of their distinct traits and concentric patterning. They are also very versatile and can go well with side stone ring designs.

Below, I’ve listed some of my favorite designs that complement the unique style of the radiant cut diamond. In fact, some of these rings are previously purchased engagement rings from other readers.

Hopefully, it can offer ideas and inspire you towards finding your perfect ring setting design.

square cut radiant diamond engagement ring solitaire design 4 prongs

A classic and affordable 4 prong solitaire ring design with a square cut radiant diamond.


platinum radiant cut diamond engagement ring design pave lotus basket

This knife edge ring has rows of pave diamonds that exhibit a vintage vibe from the engagement ring.


halo radiant cut diamond engagement ring platinum

The diamond encrusted ring setting enhances the visual size of the center stone and offers immense light play.


radiant cut diamond in french pave setting one thousand dollars best

This French cut pavé diamond engagement ring offers an unparalleled sparkle factor for a low price.


cathedral solitaire diamond engagement ring radiant 1 ct popular choice

This cathedral setting lifts the radiant cut diamond towards the eye and accentuates its outline.


twist diamond engagement ring with radiant cut center gemstone popular

An elegant twist pave setting that is perfect for small sized hands and symbolizes your intertwining love.

If you want to check out hundreds of beautifully crafted diamond engagement rings, head over to Blue Nile and James Allen today! They have a huge range of designs to cater to different tastes and budget ranges.

Summary And Recap: Where to Buy Radiant Cut Diamonds

radiant cut diamond ring with grooves

A beautiful radiant cut diamond set between 2 round brilliants.

In general, here’s what I would recommend to people who are interested in buying a radiant cut diamond. For people who are sensitive to color, a minimum color grade of “G” is recommended. In terms of clarity, I would stick with a minimum rating of “VS2”.

I don’t recommend buying blind but if you have no other methods to shop for a diamond, I would shortlist radiants with a depth percentage between 60% and 69% and a table percentage between 59% and 67%.

That will provide a good base to start filtering choices and eliminating possible options. Also, under no circumstances should you buy a diamond without a reliable lab report/certificate that recognizes its material properties and values.

The best places to buy a radiant cut diamond engagement ring would be Blue Nile and James Allen. Both are highly reliable vendors and offer fantastic sales policies where you shop with zero risks.

More importantly, both vendors offer indepth video listings that allow you to review a diamond’s outline, inclusions and cut quality. They also offer an extensive selection of GIA certified diamonds where you get to cherry pick your diamond.

If you need help with a second opinion or to pick out a well cut diamond, drop me an email or leave a comment below and I will reply to your questions. Good luck in your search!

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6 Comments

  1. Avatar
    David Lee-
    August 30, 2017 at 10:13 pm

    Hi Paul,

    Looking at a radiant square cut, not too many to choose from, can you let me know if this is a good one?

    https://www.jamesallen.com/loose-diamonds/radiant-cut/1.02-carat-e-color-vvs2-clarity-sku-2525408

    The depth is a bit out of your suggestion, so just thought I’d ask.

    Thanks!
    David

  2. Avatar
    Paul Gian-
    August 31, 2017 at 1:19 pm

    Hey David,

    The proportions like table/depth are just a rough guideline. I actually stated so beneath the table.

    The diamond you picked is a pretty diamond and has traits of a decently cut radiant diamond. Shape appeal wise, I think it is great.

    Paul

  3. Avatar
    Jill-
    September 2, 2018 at 1:27 pm

    What are the differences between a princess cut diamond and a radiant cut diamond? Would you prefer one over the other?

  4. Avatar
    Paul Gian-
    September 4, 2018 at 11:01 pm

    Interestingly from a bureaucratic point of view, the radiant cut does not exist. I know it might sound strange at first, but that is the truth when we go down to the technicalities.

    The major gemological institutes like the GIA (Gemological Institute of America) do not issue grading certificates calling these diamonds “radiant cuts”. Instead, they term it as a “cut corner rectangular modified brilliant” or “cut corner square modified brilliant” depending on the diamond’s outline. According to this terminology, a radiant cut diamond could be defined as a princess cut diamond with its corners cut off.

    The real differences between a princess cut and a radiant cut lie on the internal facet structures and the 4 truncated corners. In terms of optical performance, the princess cut has a much more linear character in the way it reflects light. On the other hand, the radiant cut diamond present a series of concentric circles radiating from the center.

    radiant cut vs princess cut

    A comparison of the radiant cut (left) vs. the princess cut (right).

    Personally, I do prefer the square princess cut over the radiant. But that’s just me and what matters most is what you like.

  5. Avatar
    Jerome-
    April 11, 2019 at 9:08 pm

    I was told that radiant cut diamonds are very forgiving when it comes to hiding inclusions and that it is able make much more of a lesser quality rough stone. Hence, the low price points. This cutting style hides flaws and color tints by making use of the excellent brilliance and scintillation properties it displays. You don’t seem to agree with that. Why?

  6. Avatar
    Paul Gian-
    April 12, 2019 at 11:03 pm

    Any diamond that has strong light return and superb sparkle will do a good job in hiding inclusions. The problem with radiant cuts is that most are extremely leaky. They do NOT have strong light performance. Now, I’m not dinking every single stone but the fact is, roughly 1 out of 100 radiant cut diamonds is somewhat cut properly. It’s hard to find but if you can find that one stone, then it can be “forgiving” when it comes to covering up flaws.

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