Radiant Cut

Square or Rectangular Cut Cornered Modified Brilliant

Radiant cut diamond - sample image
sample image
Shape: Radiant
Also known as: Square or Rectangular Cut Cornered Modified Brilliant
Cutting style: Mixed
Facets: usually between 62 - 70
L/W ratio: 1.00 - 1.35

Quick Intro

Radiant combines the brilliance and sparkle of the Round with an elegant look of the Emerald. Very versatile, suitable for any kind of jewelry including engagement rings. It was developed in the 70s by master diamond cutter Henry Grossbard. Radiants are quite similar to Princesses, but with trimmed corners and usually more rectangular shape. Perfect for those who want maximum brilliance in a square or rectangular form.

Radiant Cut: Carat to MM Chart (actual size)

The following is a chart of actual diamond sizes (from 0.25 to 10 carats) with their corresponding face-up dimensions in millimeters (length×width). Radiants can be square or rectangular. The chart below will give you an approximate idea of how big a Radiant diamond (in this case, square) of a certain weight looks or should look. The table is interactive, meaning you can click on any stone to view it in a diamond ring simulator. There you can freely experiment with different length-to-width ratios to see and compare more rectangular shapes.

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0.25 carat Radiant
3.64×3.64 mm
0.5 carat Radiant
4.59×4.59 mm
0.75 carat Radiant
5.25×5.25 mm
1 carat Radiant
5.78×5.78 mm
1.25 carat Radiant
6.22×6.22 mm
1.5 carat Radiant
6.61×6.61 mm
1.75 carat Radiant
6.96×6.96 mm
2 carat Radiant
7.28×7.28 mm
2.25 carat Radiant
7.57×7.57 mm
2.5 carat Radiant
7.84×7.84 mm
2.75 carat Radiant
8.1×8.1 mm
3 carat Radiant
8.33×8.33 mm
3.25 carat Radiant
8.56×8.56 mm
3.5 carat Radiant
8.77×8.77 mm
3.75 carat Radiant
8.98×8.98 mm
4 carat Radiant
9.17×9.17 mm
4.25 carat Radiant
9.36×9.36 mm
4.5 carat Radiant
9.54×9.54 mm
4.75 carat Radiant
9.71×9.71 mm
5 carat Radiant
9.88×9.88 mm
5.25 carat Radiant
10.04×10.04 mm
5.5 carat Radiant
10.2×10.2 mm
5.75 carat Radiant
10.35×10.35 mm
6 carat Radiant
10.5×10.5 mm
6.25 carat Radiant
10.64×10.64 mm
6.5 carat Radiant
10.78×10.78 mm
6.75 carat Radiant
10.92×10.92 mm
7 carat Radiant
11.05×11.05 mm
7.25 carat Radiant
11.18×11.18 mm
7.5 carat Radiant
11.31×11.31 mm
7.75 carat Radiant
11.43×11.43 mm
8 carat Radiant
11.56×11.56 mm
8.25 carat Radiant
11.68×11.68 mm
8.5 carat Radiant
11.79×11.79 mm
8.75 carat Radiant
11.91×11.91 mm
9 carat Radiant
12.02×12.02 mm
9.25 carat Radiant
12.13×12.13 mm
9.5 carat Radiant
12.24×12.24 mm
9.75 carat Radiant
12.34×12.34 mm
10 carat Radiant
12.45×12.45 mm
Length-to-width ratio: 1

Size Comparison With Other Shapes

When it comes to size, Radiants fall right in the middle. They typically look larger than Asschers, Princesses, Cushions, Hearts, and Emeralds, and smaller than Rounds, Ovals, Pears, Trillions, and Marquises. Their squarish or rectangular appearance, however, can create an illusion of somewhat greater size.

Here is the size comparison of Radiant cut with diamonds of all other shapes. The percentages show average face-up size difference. Radiants tend to be slightly smaller than Rounds (5%) and pretty much on par with Emeralds:

Buying Guide For Radiants

As all brilliant cuts, Radians hide inclusions quite well. This means you can go relatively low on the clarity scale, down to SI (SI1 or even SI2, if it's eye clean). For color, H or higher is recommended. The gemological labs (like GIA or AGS) don't grade cut quality for this shape, however, if you stick to the cut parameters defined below, you should be OK. Avoid stones that are too deep or too shallow. Make sure corners are even and symmetrical.

Here is a guide on what to look for and what to avoid:

Look for:
  • Color: H or higher [depends on a setting]
  • Clarity: SI or better [explain]
  • Cut parameters:
    • Depth: 59% - 70%
    • Table: 58% - 70%
    • Polish/Symmetry: Good or better
    • Length-to-width ratio: 1.00 - 1.35
  • Diamonds certified by GIA or AGS [explain]
  • Eye-clean

Watch out for:
  • Non-symmetrical corners
  • Inclusions visible to the naked eye
  • Extremely thin or extremely thick girdle
  • Fair or Poor symmetry
  • Strong blue fluorescence [explain]
  • Diamonds without GIA or AGS certification [explain]

Did You Know?

  • A Radiant diamond can have up to 70 facets. Now that's a lot of facets. For comparison, Round will have 58. All those facets give exceptional fire and brilliance, and create a unique appearance of cracked, crushed ice. For added bonus, this also makes them more forgiving of inclusions.

Where To Buy Radiant Diamonds?

It's simple: for best value, shop online. Online vendors almost always have better prices than traditional stores. They also have huge selections and with today's technology you can now easily inspect any diamond up-close in 360-degree view. It's easy and safe to buy online. Here are the most recommended online retailers:

Compare Radiant with another diamond

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carat vs. length* width* depth*
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Color Recommendation For Radiant Diamonds

Radiants show color quite strongly, so it's recommended not to go too low on the color scale. The choice of color also depends on a setting:

Solitaire Small side-stones Substantial side-stones
White gold/Platinum H+ G+ same as side-stones+
Yellow gold J+ I+ same as side-stones+
e.g. pave setting e.g. three-stone setting
Note: If side-stones are of any significant size (like in three-stone settings), you should at least match the color of the center stone with the color of the side stones, otherwise the center stone might look out of place (a bit "off-white").

For best value, go with the minimum recommended color for a particular type of setting. Color variations between H graded and higher colored Radiant cuts are so slight that it's almost impossible to tell the difference, especially when diamonds are mounted. The difference in price, however, can be quite considerable.

Clarity Recommendation For Radiant Diamonds

Radiants are quite forgiving of inclusions, so you can go relatively low on a clarity scale, as long as the diamond is eye-clean. SI1, SI2 clarity or higher is recommended.

Note: You can always go lower in clarity, but it's going to get increasingly difficult to find an eye-clean Radiant below the minimum recommended SI2 grade.

For best value, go with the lowest clarity possible that is still eye-clean. If a diamond is eye-clean, then it doesn't really matter, if it's flawless or SI2. It will look the same, provided all other characteristics are the same.
About Diamond Clarity
Diamond clarity refers to the presence and visual appearance of the flaws inside a diamond (called inclusions) or on its surface (called blemishes). Clarity tells you to what degree these imperfections are present.

The amount of inclusions and blemishes is directly correlated to a diamond's value. Fewer imperfections mean higher price and vice versa.

Gemological laboratories grade diamond clarity as Flawless (FL), Internally Flawless (IF), Very Very Slightly Included (VVS1,VVS2), Very Slightly Included (VS1,VS2), Slightly Included (SI1,SI2), and Included (I1,I2,I3).

GIA and AGS Certified Diamonds

Professional and unbiased assessment of a diamond's characteristics is stated on a diamond grading report, commonly referred to as a certificate. Certificate, while not 100% reliable, is essential in determining a diamond's value.

The standard for diamond grading is pretty much set by GIA - Gemological Institute of America. They are the most reputable and consistent lab in the industry. AGS (American Gemological Society) is not far behind.

If a diamond is not certified by GIA or AGS, you can be pretty much certain that you are looking at lesser quality than indicated. This puts you in a bad position of not knowing the true diamond characteristics, which almost always results in overpaying. That is why a certificate from a well-respected grading lab is so important.

The bottom line: Make sure to always buy a diamond certified by either GIA or AGS. That's the only way of truly getting the quality you expect.

Diamonds with Blue Fluorescence

Blue fluorescence can have a positive, negative, or zero effect on a diamond. Diamonds in the lower color range (H or lower) can benefit from it, as it can make them look whiter, more colorless. On the other hand, strong fluorescence can cause a stone (especially in the higher color range D-G) to appear hazy or milky under certain light conditions. One of the biggest benefits of fluorescent diamonds is that they generally cost less.

GIA grades fluorescence as None, Faint, Medium, Strong, and Very Strong.

Faint fluorescence will have zero effect on color and overall appearance. Fluorescence of this type is not an issue and shouldn't be a purchasing factor.

Medium fluorescence will in most cases have zero to very small influence on color and overall appearance, however, colorless diamonds can sometimes exhibit negative effects and should be examined in different light conditions before purchasing.

Strong/Very Strong fluorescence requires caution. Generally, it's not a good idea to buy a colorless diamond with Strong/Very Strong fluorescence. As for lower color diamonds, even they can sometimes look hazy with strong fluorescence, so never buy a stone with this type of fluorescence without careful visual inspection.

If you're interested in fluorescent diamonds that have been carefully examined and do not display any negative effects of fluorescence, I recommend Brian Gavin's Blue Diamonds. Those are definitely top of the line and a great value.

Diamonds Without GIA or AGS Certificates

The problem with diamond grading labs other than GIA or AGS is that they are looser and more inconsistent in their grading standards. A GIA color H is an IGI color G and an EGL/HRD color F. The same goes for clarity.

While it's true that IGI, EGL, and HRD diamonds are sold at a discount, you can be certain that the same stones would cost less, if they would be certified by GIA or AGS. Why? Because they would get lower grades and thus lower price. Lower than discounted IGI, EGL, and HRD stones with higher grades.

Diamond merchants use IGI, EGL, HRD, and alike to maximize their profits. They know they can sell diamonds with inflated grades for more, even if they're sold at a substantial discounts. Some merchants also use their in-house certification, usually for the sole purpose of increasing their profits. These kinds of certificates are meaningless.
The bottom line: If you don't want to overpay and want to know exactly what kind of quality you're getting, then avoid diamonds without GIA or AGS certification.

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