Buyer's Guide to Radiant Cut Diamond & Quality Insights

Buyer's Guide to Radiant Cut Diamond & Quality Insights

Buyer's Guide to Radiant Cut Diamond & Quality Insights

Posted by Sharif Khan on 3rd Jun 2022

radiant cut ratio

Key Takeaways:

  • You cannot go wrong with radiant-cut diamonds in terms of fire and brilliance. The shape has 70 facets and a brilliant-cut facet pattern.
  • Make sure that you are familiar with square and rectangular radiant-cut diamonds. See the image above as it illustrates perfect ratios for both types.
  • We recommend a length-to-width ratio of 1-1.05 for square and 1.16-1.3 for rectangular, depending on how elongated you want the stone to look.
  • While analyzing the cut, look for a 57-69% table and a 58-70% depth. Check out the chart below for exact numbers and other important information about the cut.
  • Buy a radiant-cut diamond graded by the GIA or the AGS.
  • While prioritizing the 4Cs, if you want a premium radiant cut in the investment-grade range, go for this ( example 1). A stone like this can be considered to maximize quality and carat weight ( example 2). Consider a stone in this range if you do not mind compromising slightly on quality to maximize carat weight ( example 3). Finally, one way to maximize cut, clarity, and carat weight is to compromise on color. In this case, something like this might be the way to go ( example 4).

Here is a list of our top websites for diamond and engagement rings to consider.

radiant cut proportions

Overview Radiant Cut:

Radiant-Cut diamond is one of our favorite diamond shapes. The 70 facets in a radiant-cut diamond allow it to emanate tremendous shine. A radiant-cut diamond is a vibrant and exuberant square/rectangular stone with a complete brilliant-cut facet pattern applied to its crown and pavilion. It is also an excellent reflector of light, having served as an alternative to the emerald-cut diamond since its invention. Since the 1970s, radiant-cut diamonds have been a popular choice. All credits go to Henry Grossbard, the mastermind behind the shape of the radiant-cut diamond.

Tools like James Allen's 3D 360 Degree 40X Magnified Videos can help assess how a change in proportions and length-to-width ratios affect the appearance of a radiant-cut diamond. Try to use the outlined proportions below and play with their search filter to understand what a good option for you might be.

Analyzing Radiant Cut Diamond:

Depth %
  • Poor/Far: <52 or >80 / 52-80
  • Good: 57-59 / 71-74.5
  • Very Good: 58.8-70/67-70.1
  • Excellent: 61.3-67
  • Table %
  • Poor/Fair: <50 or >80/50-52.5 or 75.5-80
  • Good: 53-57/74
  • Very Good: 58-61/71
  • Excellent: 62-70
  • Culet
  • Poor/Fair: Large/Very Large
  • Good: Medium
  • Very Good: None/Very Small
  • Excellent: None
  • Girdle
  • Poor/Fair: Ex. Thin – Ex. Thick
  • Good: Very thin - thick
  • Very Good: Very thin - slightly thick
  • Excellent: Very thin - slightly thick
  • Length to Width Ratio for Square Cut
  • Poor/Fair: >1.09 /1.07-1.09
  • Good: 1.05-1.06
  • Very Good: 1.00-1.04
  • Excellent: 1.00-1.04
  • Length to Width Ratio for Rectangular Cut
  • Poor/Fair: <1.08 or >1.41/1.07-1.08
  • Good: 1.09-1.13/1.37-1.41
  • Very Good: 1.14-1.20/1.32-1.36
  • Excellent: 1.20-1.31
  • James Allen

    The chart above serves as a general guideline when evaluating the cut of a radiant diamond. The length-to-width ratio of 1.00-1.04/1.20-1.31 is considered classic for the diamond's square and rectangular shapes, though personal preference could override it. If you appreciate the sophistication and the fire of emerald and round diamonds, respectively, you should consider the radiant-cut diamond. It will prove a perfect combination of a round and an emerald diamond in terms of fire and sophistication. You can also obtain a perfect combination between the cushion and the princess-cut if you look at its cropped corner square shape. The nice bridge between the cushion and princess-cut makes it look beautiful when set with round or square corners.

    Evaluating Radiant Cut Color:

    Like evaluating the color in other diamond shapes, the color in a radiant-cut diamond is critical. The higher the color grade, the better. In our experience, many buyers prefer warmer colors over colorless options due to the price difference. The warmer colors refer to the near-colorless range of G-I color diamonds in the color spectrum, while the colorless ones refer to D-F color diamonds. The price premium would be much lower if you want to get a lower color grade radiant-cut diamond at a cheaper cost.

    For more detailed information on the color of cushion-cut diamonds, use the table below.

    < 0.50 Carat
  • Poor/Far: >M/ L-M
  • Good: I-K
  • Very Good: G-I
  • Excellent: D-G
  • 0.51 – 1.0 Carat
  • Poor/Fair: J-K / >L
  • Good: I
  • Very Good: H
  • Excellent: D-G
  • 1.0 – 2.0 Carat
  • Poor/Fair: J-K / >I
  • Good: H-I
  • Very Good: G
  • Excellent: D-F
  • >2.0 Carat
  • Poor/Fair: I-K / >I
  • Good: I
  • Very Good: G-H
  • Excellent: D-F
  • Fluorescence
  • Poor/Fair: Very Strong
  • Good: Strong 
  • Very Good: Medium Blue/Faint/None
  • Excellent: None
  • Choosing Radiant Cut Clarity:

    Choosing the kind of clarity is subjective in a radiant-cut diamond. Choose one that meets your standards in terms of clarity. Our customers have a unique standard for clarity and color; some want a flawless diamond, while others are perfectly comfortable with a slight inclusion if it is not easily noticeable. In our experience, any clarity above SI2 (GIA standards) will be excellent.

    < 0.50 Carat
  • Poor/Far: I2 / >I2
  • Good: I1-I2
  • Very Good: SI1-SI2
  • Excellent: FL-VS2
  • 0.51 – 1.0 Carat
  • Poor/Fair: I2 / >I2
  • Good: SI2
  • Very Good: SI1-SI2
  • Excellent: FL-VS2
  • 1.0 – 2.0 Carat
  • Poor/Fair: SI2-I1 / >I1
  • Good: SI1-SI2
  • Very Good: WS2-VS2
  • Excellent: FL-VS1
  • >2.0 Carat
  • Poor/Fair: >SI2
  • Good: SI1-SI2
  • Very Good: VS1-SI1
  • Excellent: FL-WS2
  • Suggested carat weight, cut, color and clarity of Radiant Cut Diamond for people with budget constraints

    Excellent Choice

    • Weight of at least 1.0 carat
    • Very Good to Excellent Polish and Symmetry
    • G or above in color
    • Clarity of SI1 or higher
    • No Fluorescence
    • Length/width ratios: 1.0-1.04 for a square or 1.20-1.35 for a rectangular shape

    Very Good Choice

    • Weight of at least 0.90 carat
    • Good to Excellent Polish and Symmetry
    • H or above in Color
    • Clarity of SI1 or higher
    • None, faint or medium blue Fluorescence
    • Length/width ratios: 1.0-1.04 for a square or 1.20-1.35 for a rectangular shape

    Good Choice

    • Weight of at least 0.80 carat
    • Good to Very Good Polish and Symmetry
    • I or higher in Color
    • Clarity of SI1 or higher
    • None, faint or medium blue Fluorescence
    • Length/width ratios: 1.0-1.04 for a square or 1.20-1.35 for a rectangular shape.

    Frequently Asked Questions About Radiant Cut Diamonds:

    Between the square and rectangular radiant-cut diamonds, which one is better?

    It entirely depends on your budget; we have seen both options in the market. While the elongated ones look more prominent, the square radiant cuts have a beautiful and elegant look to them as well.

    What is the best alternative to radiant-cut diamonds?

    Radiant-cut diamonds are alternatives to emerald-cut diamonds that have more of a step-cut and fewer facets. If you want large and deep facets, emerald-cut diamonds will be ideal. But if you desire sparkle and radiance, a radiant cut should be the choice.

    Why are radiant-cut diamonds cheaper than round-cut diamonds?

    They are not necessarily cheaper than round diamonds. Round diamonds have a large surface area, and therefore a one-carat round diamond requires a bigger rough diamond than a radiant cut. (For example, the average surface size of a 1 carat round diamond is about 6.4mm, while it would be in the 5.5mm range for a square radiant cut.) So, while they are of similar carat weight, the cutter had to sacrifice a bigger rough diamond to get a 1 carat round diamond than s/he had to for a radiant cut. (The price reflects the difference.)

    Square vs rectangular radiant cut

    Be sure to check out our loose diamond page to compare the actual prices of different companies.