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What Is An Radiant Cut Diamond? - Buying Guide

Radiant cut diamond.

The radiant cut diamond is a square or rectangular shaped hybrid cut that combines the brilliance and depth of the round brilliant cut, emerald cut and princess cuts, the radiant is the most brilliant of all the squared shapes making it both a beautiful and dramatic choice.

Radiant Cut Diamond

Radiant cut diamond.

Due to its design, this shape requires more carat weight in the depth to maximize brilliance.

Radiant Cut Diamond Buying Guide


Also referred to as: SQUARE - OR RECTANGULAR MODIFIED BRILLIANT


Radiant Cut Diamond Quick Guide


Unique Features
Signature trimmed edges, brilliant step cut
Facets
Usually 70
L/W Ratio
1.00 - 1.05 (square) > 1.05 - 1.50 (rectangular)
Origin
1977
Expert Tip
Hides inclusions well


Radiant Cut Diamond Ring

Radiant Cut Diamond Ring

Radiant cut diamond ring.


Radiant Cut Diamond Features

Radiant Cut Diamond Features

Radiant cut diamond features.

The Radiant is a unique and hybrid cut comprised of 70 facets and distinctive trimmed edges. Square-shaped radiants typically have ratios between 1.00 and 1.05 while rectangular radiants can have ratios from over 1.05 anywhere up to 1.50.

Its versatile design combines the brilliance and depth of the round, emerald and princess cuts making it a popular choice for all types of jewellery.

As it is a patented cut, it may be referred to as a Cut-Cornered Square on a laboratory certificate (eg. GIA or AGS), or a Rectangular Brilliant if it has a ratio greater than 1.05.

Radiant Cut Diamond Expert Guide

Because of its extra facets, the radiant cut can disperse more light through the diamond making it one of the most brilliant of all square and rectangular shaped diamonds. It also hides inclusions more efficiently than other shapes. As it is a hybrid cut combining the features of both brilliant and step cuts, the radiant is the ideal compromise and the perfect solution for someone who wants to have it all. There are diverse preferences when it comes to shape in radiant cut diamonds, from a perfectly square 1.00 length to width ratio (any ratio of 1.05 or less will appear square to the naked eye), to a more traditional rectangle. The rectangular radiant cut is an excellent option for buyers who like the emerald cut shape, but want something with the brilliance of a round. The square radiant looks very similar to a princess cut, but with cropped corners. Once set, a square radiant and a princess look virtually identical, since the prongs cover the corners.

The radiant cut diamond is the first square cut (the second being the princess) to have a complete brilliant cut facet pattern applied to both the crown and pavilion, creating a vibrant and lively square diamond. First popular in the 1980's, the cropped corner square shape of the radiant is a nice bridge between a cushion and a princess cut, and for that reason looks beautiful set with both rounded or square cornered diamonds. In longer (more rectangular) radiant cut diamonds, a bow-tie effect is more likely (although not as common as in oval, marquise, and pear cuts), varying from near invisible to severe. The visibility of a bow-tie effect cannot be ascertained by reviewing the diamond certificate or dimensions, but only upon visual inspection.

Radiant Cut Diamond Bow-tie

Radiant cut diamond bow-tie.

Like other fancy shapes, radiant diamonds can exhibit a dramatic visual problem, the bow-tie effect. Elongated rectangular radiant cut diamonds are particularly prone to this defect, which is caused by the stone being improperly cut and proportioned so that close-up objects darken the stone across its circumference in shape, resembling a bowtie. If you are purchasing a radiant diamond elsewhere, always ensure that your diamond is free of a noticeable bow-tie.

Radiant Cut Diamond - Cut Guide

Diamond cut quality is the main factor determining a diamonds appearance and level of brilliance and sparkle. Since the GIA doesn't provide cut grading for radiant cut diamonds, you will need to be very careful when selecting one.

Make sure you have checked the corners, they should be even. not too wide or too narrow. The symmetry is the key to maintain the overall beauty of the diamond.

The chart below serves as a general guideline for evaluating the cut of a radiant cut diamond:

Swipe left to see more.

Radiant Cut Diamond Excellent Very Good Good Fair Poor
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Depth refers to the distance between the culet and the table when a diamond is viewed from the side.

The depth % of a diamond is calculated by dividing the depth of the diamond by the width of the diamond. So, if a diamond is 3 mm in depth, and 4.5 mm in width, its depth % is 66.7.

The lower the depth %, the larger a diamond of a given carat weight will appear when viewed from above (since more of the diamond's size is in its width vs. in its depth).

Depth % is incorporated in the cut grade of a diamond. For this reason, when purchasing a diamond, use the cut grade first (since it balances multiple measurements, not just depth %). Once two diamonds of equal cut are being compared, consider depth % as a further refinement.

Learn more about the anatomy of a diamond.

61 - 67 59 - 60.9 or 67.1 - 70 57 - 58.9 or 70.1 - 74 54 - 56.9 or 74.1 - 79 <54 or >79
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The table is the uppermost, flat surface of a diamond, which runs parallel to the plane of the girdle.

The table % of a diamond is calculated by dividing the width of the table facet by the width of the diamond. So, if the table facet is 3 mm across, and the diamond is 4.5 mm wide, its table % is 66.7.

Table % is incorporated in the cut grade of a diamond. For this reason, when purchasing a diamond, use the cut grade first (since it balances multiple measurements, not just table %). Once two diamonds of equal cut are being compared, consider table % as a further refinement.

Learn more about the anatomy of a diamond.

61 - 69 57 - 60 or 70 - 72 54 - 56 or 73 - 74 51 - 53 or 75 - 79 <51 or >79
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A diamond's symmetry is the arrangement, size, and shaping of diamond's facets. The facets are the flat planes that run along the surfaces of the diamond. Symmetry is angles and lines that form the placement of the facets. Nowadays, symmetry is completely controlled by the manufacturing process. Machines very carefully cut diamonds to produce the most accurate shapes. However, at times the diamond cutter will leave a symmetry imperfection in the diamond in order to prevent a different inclusion from showing in the finished diamond. Symmetry is a subset of the diamond's cut grade.

Learn more about diamond symmetry.

Good to excellent Good to excellent Good to excellent Fair to Excellent Poor to Excellent
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The term "polish" refers to the overall condition of the surfaces of a finished diamond. A rating is assigned based on the amount of polishing lines that are visible. These polishing lines are caused by very small diamond crystals which are embedded in the polishing wheels used by diamond cutters to polish the surface of the diamond after cutting. Diamond polish is important because it can affect the degree to which light is able to pass through a diamond, rendering it more or less brilliant. Diamonds that are laboratory certified with a good, very good, or excellent polish rating are the most desirable. Diamonds that have poor polish will be less brilliant and not as desirable or valuable. Reputable jewellers diamonds are graded after examining the diamond facet by facet.

Learn more about diamond polish.

Good to excellent Good to excellent Good to excellent Fair to Excellent Poor to Excellent
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The girdle is the outer edge of the diamond, where the crown (top) meets the pavilion (bottom).

A girdle may be faceted (a series of tiny polished sides going around the diamond), bruted (a single continuous unpolished surface going round the diamond; no longer common), or polished (a bruted girdle that has been polished smooth). Whether a girdle is faceted, bruted, or polished usually has no impact on the appearance or value of the diamond.

The girdle is described according to its width. Often, the width of the girdle varies at different points around the diamond, and is quoted in a range designating the thinnest and thickest point along the girdle (e.g. "Thin - Medium" means the diamond's girdle varies in width from thin at the narrowest point to medium at the widest point).

Learn more about the anatomy of a diamond.

Very Thin - Slightly Thick Very Thin - Slightly Thick Very Thin - Thick Very Thin - Very Thick Ex. Thin - Ex. Thick
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The culet (pronounced cue-let) is the small area at the bottom of a diamond's pavilion. The culet can be a point or a very small facet sitting parallel to the table.

The culet size as determined by the GIA, is shown using the following scale:

None, Very Small, Small, Medium, Slightly Large, Large, Very Large.

Any culet size of Medium or smaller will be invisible to the naked eye, and have no negative impact on a diamond's appearance. However, if a culet is Slightly Large or larger, it may allow light entering from the crown to pass straight through the culet facet, reducing the diamond's brilliance. This may also make the culet appear as an inclusion, or create a dead area on the diamond where the light is escaping through the bottom.

Learn more about the anatomy of a diamond.

None Very Small Small Medium > Medium
×

The length to width (L/W) ratio is calculated by dividing a diamond's length (the longer measure) by its width (the shorter measure that runs perpendicular to length).

For example, an Oval Cut diamond that is 5.00 mm in length and 3.3 mm in width will have a L/W ratio of 1.50 (5.00/3.33). A perfectly round or square diamond will have a length to width ratio of 1.00, but many will be off slightly since they are often not perfectly cut. Any L/W ratio of 1.05 or less will appear perfectly round or square to the naked eye.

L/W ratio is more commonly used in fancy shapes. There is no "ideal" L/W ratio in a fancy shape diamond. What is important is what looks pleasing to you.

Square
1.00 - 1.03 1.00 - 1.03 1.04 - 1.05 1.06 - 1.08 > 1.08
×

The length to width (L/W) ratio is calculated by dividing a diamond's length (the longer measure) by its width (the shorter measure that runs perpendicular to length).

For example, an Oval Cut diamond that is 5.00 mm in length and 3.3 mm in width will have a L/W ratio of 1.50 (5.00/3.33). A perfectly round or square diamond will have a length to width ratio of 1.00, but many will be off slightly since they are often not perfectly cut. Any L/W ratio of 1.05 or less will appear perfectly round or square to the naked eye.

L/W ratio is more commonly used in fancy shapes. There is no "ideal" L/W ratio in a fancy shape diamond. What is important is what looks pleasing to you.

Rectangle
1.20 - 1.30 1.15 - 1.19 or 1.31 - 1.35 1.10 - 1.14 or 1.36 - 1.40 1.08 - 1.09 or 1.41 - 1.50 <1.08 or >1.50

Radiant diamond cut guide.

Radiant Cut Diamond Ratio

Radiant diamond length to width ratio.


Radiant Cut Diamond - Color Guide

Evaluating color in radiant cut diamonds is subjective. Keep in mind that many buyers may actually prefer the ever so slightly warmer colors of a G-H diamond over the cool colorlessness of a D-F diamond. In fact, most of the premium in price associated with radiant cut diamonds at the higher end of the color scale is driven by supply and demand; customers want the D-F color grades, and are willing to pay a premium to get them. In a world without diamond color grading, the price premium for higher grades would be much lower, as the actual differences in color are difficult to perceive.

Color of radiant cut diamonds is graded on a scale from D to Z. where D signifies a completely colorless diamond and Z means an easily noticeable yellow or brown tint.

As a general rule, smaller radiant cut diamonds hide color better than larger ones. but the differences in color in radiant diamonds are easier to notice than in other diamond shapes. For this reason, it is recommended to opt for H color or better to have a diamond that will appear white and colorless to the naked eye. The color chart below provides a general guide for evaluating color in radiant cut diamonds:

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Radiant Cut Diamond Excellent Very Good Good Fair Poor
< .50 ct. D - G H - I J - K L - M > M
.51-1.0 ct. D - F G H - I J - K > K
1.0-2.0 ct. D - F D - F G - H I - J > J
> 2.0 ct. D - F D - F G H - I > I
×

Fluorescence refers to a diamond's tendency to emit a soft colored glow when subjected to ultraviolet light. Roughly 30% of diamonds fluoresce to some degree.

Colorless (D-F) fluorescent diamonds sell at up to a 15% discount since the fluorescence is perceived as a defect, even though the visible effects of Faint to Medium fluorescence are perceptible only to a gemologist using a special UV light source.

Because the fluorescent glow is usually blue (which is the complementary color to yellow) fluorescence can make diamonds of I-M color appear up to one grade whiter. For this reason, I-M diamonds tend to sell at a slight premium when they possess Medium to Very Strong fluorescence.

Exercise caution in purchasing a diamond with Strong fluorescence in D-F color diamonds or Very Strong fluorescence in G-H color diamonds (which do not possess enough body color to offset the higher degree of fluorescence).

Learn more about diamond fluorescence.


None Faint - Med Strong Very Strong Very Strong

Radiant diamond color guide.

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Radiant Cut Diamond Color

Radiant cut diamond color.

Radiant Cut Diamond - Clarity Guide

Like color, evaluating clarity in radiant cut diamonds is subjective. GIA provides excellent help with their clarity grades. Still, it is important to understand that each customer will have a unique standard for clarity. Some may be perfectly comfortable with an inclusion as long as they cannot easily see it. Others may insist on a more technically flawless appearance. Because of its brilliance, a radiant cut is more forgiving of inclusions than other square cuts (like asscher and emerald), especially when viewed with the naked eye.

The GIA grades clarity of round cut diamonds on a scale from FL to I3, where FL means a flawless diamond and I3 indicates a heavily included diamond:

As mentioned, due to the brilliant-cut facet pattern, radiant cut diamonds hide blemishes fairly well, especially in comparison to emerald cut diamonds. Moreover, smaller radiant cut diamonds hide imperfections better than larger ones do, which is why if you are going to purchase a smaller diamond you may opt for a lower clarity grade while keeping an eye-clean appearance. The clarity chart below provides a general guide for evaluating clarity in radiant cut diamonds:

Swipe left to see more.

Radiant Cut Diamond Excellent Very Good Good Fair Poor
< .50 ct. FL - VS2 SI1 - SI2 I1 I2 > I2
.51-1.0 ct. FL - VS1 VS2 - SI1 SI2 I1 - I2 > I2
1.0-2.0 ct. FL - VVS2 VS1 - VS2 SI1 - SI2 I1 > I1
> 2.0 ct. FL - VVS2 VS1 - VS2 SI1 SI2 > SI2

Radiant diamond clarity guide.

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Radiant Cut Diamond Clarity

Radiant cut diamond clarity.


Radiant Cut Diamond History & Background

The first Radiant cut was designed by Henry Grossbard of the Radiant Cut Diamond Company (RCDC) in 1977. Prior to this invention, all diamonds with square or step cut edges appeared less brilliant.

Grossbard invented a hybrid cutting style that revolutionised the industry's perceptions towards square or rectangular diamonds as he managed to create a step cut diamond that possessed equal brilliance to triangular faceted diamonds such as the oval and pear.

The Radiant is also the first cut to have a brilliant-facet pattern applied to both the crown & pavilion. RCDC launched the Original Radiant Cut diamond brand in 2002.

Radiant Cut Diamond history

Radiant cut diamond history.

Learn more about what you need to know in our ultimate buying guide, if you're thinking of buying a radiant cut diamond. We break it all down from pricing, other shapes comparison and engagement ring setting choices.