Guide to 7 Factors that Make Oval Cut Diamonds Shine

Guide to 7 Factors that Make Oval Cut Diamonds Shine

Guide to 7 Factors that Make Oval Cut Diamonds Shine

Posted by Sharif Khan on 10th Jul 2021

Oval cut diamonds are full of fire and brilliance, and their elongated shapes make them look big in each carat weight. Additionally, their modified brilliant cut allows them to have amazing sparkle just like round cut diamonds.

A dull-looking oval cut diamond is not easy to avoid, especially when assessing the quality of its cut. Therefore, when considering this alluring gemstone, carefully review the following seven factors and our recommended cut proportions below before making a final purchase. 

Oval cut diamond ring

7 Important Factors in Oval Cut Diamonds:

  1. According to the Blue Nile and James Allen (two of our favorite online retailers), oval cut diamonds are in the second tier of most popular diamond shapes in 2021, right next to traditional round cut diamonds. In order to buy the most recent cut shape, look for an oval cut with faceting like the one shown in image four below.
  2. In terms of cut, a depth of 55-63% and a table of 52-63% is preferred. Follow our chart below carefully while analyzing the cut of an oval diamond.
  3. The bow-tie effect is a critical factor to consider, and if an oval cut diamond is poorly cut, it will have a large bow-tie effect. Review our instructions below and assess each diamond carefully for its bow-tie effect before placing an order online.
  4. Oval cut diamonds have an amazing spread and surface size (they look big) but you must buy a diamond with the right length-to-width ratio. Oval cut diamonds in the range of 1.38%-1.55% ratio are perfect, depending on how round or elongated you want the diamond to look. See our chart below for details.
  5. When comparing different oval cut diamonds within a given budget range, if you do not have budget constraints and want a high quality stone, look for something like this (option 1). If you are trying to maximize carat weight within your budget without compromising on quality, look for an oval cut diamond within this range (option 2). If you do not mind compromising more on the other 3Cs (cut, color, clarity) to maximize the carat weight (as long as the stone is eye-clean), something like this might work for you (option 3). Finally, if you want to compromise on one C to maximize on the other 3Cs, compromise on color while prioritizing clarity and cut (option 4).
  6. Always buy an oval cut diamond that is either graded by GIA or AGS.
  7. Fluorescence is a negative factor in oval cut diamonds. Avoiding fluorescence in D-E color diamonds is best, while faint is okay in F to G color diamonds, and medium blue is acceptable in H and I color diamonds.  

Recommended proportions for Oval cut diamondsoval cut proportions

Examples of Length-to-Width Ratios oval cut ratio

Buying Oval Cut Diamonds:

While oval cut diamonds have existed for centuries, Lazare Kaplan perfected its cut in the 1960s. These luminous gems are different from your day-to-day diamond shapes as they possess the fire and brilliance of a round cut diamond. This shape is cut into a perfectly symmetrical design, making it an ideal choice for individuals who like round diamonds but desire something more distinct.

Like other fancy diamond shapes, preferences of an oval cut diamond also vary by length-to-width ratios of the cut. A classic oval cut diamond will have its length-to-width ratio of 1.50 or in the approximate range of 1.36-1.60. This range stretches out the outline enough to be different from a round cut. If the elongation ends up too long, the cut will look similar to a marquise cut.

The "bow-tie effect" is present in almost all oval, marquis, and pear cut diamonds. Since it carries importance in analyzing an oval cut diamond, please refer to our post on the effect of bow-tie on fancy cut diamonds for more information. In our opinion, a small "bow-tie effect" is a plus for an oval cut diamond. Likewise, please avoid a large "bow-tie effect" because it indicates that the diamond has been cut poorly.

Here is a list of our top vendors for loose diamonds and engagement rings to consider.

Analyzing the Cut in Oval Diamonds:

Hint: Use tools like James Allen's Video 3D 360 Degree 40X Magnified Technology to compare different diamonds and understand the effect of proportions on their cut and shape. It can also help in figuring out what might be an optimal length-to-width ratio for you.

Depth %
Poor/Fair: <51 or >75/71-75
Good: 54-56/ 66-71
Very Good: 56-58/62-66
Excellent: 57-62
Table %
Poor/Fair: <51 or >72 / 70-72
Good: 50 / 66-69
Very Good: 52/65
Excellent: 53-64
Poor/Fair: Very Large/Large
Good: Slightly large
Very Good: Medium/Very Small
Excellent: None
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
Poor/Fair: >1.66 /1.62-1.66
Good: 1.57-1.61
Very Good: 1.51-1.56
Excellent: 1.36-1.50

The chart above serves as a general guideline when evaluating the cut of an oval cut diamond. A classic oval diamond would have a length-to-width ratio of 1.50. However, deciding the right length-to-width ratio often comes down personal preference/taste (we love 1.40 to 1.55 ranges).

A GIA graded report include precise measurements that be used to calculate the length-to-width ratio of an oval cut diamond (simply divide the length by width to get the right ratio). 

oval cut styles

When it comes to the shape of the diamond, buy one with similar facets as the middle one in the image above (check the GIA report for its cutting style). The styles on the left and right are older versions and the one in the middle is the modern modified brilliant-cut. It has 57-58 facets just like a round brilliant cut would have and will give the best brilliance/fire.

James Allen

Evaluating the Color in Oval Diamonds:

Color is an important C while considering oval cut diamonds. Therefore, prioritize color after cut for optimal brilliance. If you do not have significant budget constraints, aim for a D-F color oval cut diamond. However, G is also a great color and is not too far off from the colorless range as far as the beauty of the stone is concerned. H and I are good budget options. The good side to H and I color diamonds is that the price premium for these stones is much lower.

For more detailed analysis of color in oval cut diamonds, use the table below as a reference.

< 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
Good: I/H
Very Good: D-G
Excellent: D-F
>2.0 Carat
Poor/Fair: >J
Good: H-I
Very Good: D-G
Excellent: D-F
Poor/Fair: Very Strong/Strong
Good: Medium
Very Good: Faint
Excellent: None

ideal oval cut

Ideal Length-to-Width Ratio of 1.45

Understanding Clarity in Oval Diamonds:

Choose an oval cut diamond that meets your standards in terms of clarity. Each buyer has a unique take on the clarity grade of a diamond. Some want a flawless diamond while others are perfectly comfortable with some inclusions as long as the diamond is eye clean.  

GIA is the best in terms of consistently and accurately grading diamond clarity. In our opinion, most SI1 diamonds in the 1-1.3 carat range are eye clean while it is generally recommended to consider VS2 in diamonds above 1.5 carat in weight. 

The chart below serves as a general guide for evaluating clarity in oval diamonds.

< 0.50 Carat
Poor/Far: >I1/ I1
Good: SI2
Very Good: SI1-VS2
Excellent: FL-VS1
0.51 – 1.0 Carat
Poor/Fair: > I1
Good: SI2
Very Good: SI1-VS2
Excellent: FL-VS1
1.0 – 2.0 Carat
Poor/Fair: >I1
Good: SI2-SI1
Very Good: VS2
Excellent: FL-VS1
>2.0 Carat
Poor/Fair: >I1
Good: SI2-SI1
Very Good: VS1-VS2
Excellent: FL-WS2

Prioritizing the 4Cs in Oval Cut Diamonds:

Over the last decade, our clients prioritized and compromised on the 4Cs in the following manner:

Scenario 1: Quality was their primary concern. In this option, they would go for the best of the 4Cs in each given carat weight range. Any diamond above 1 carat, F, VS1, excellent cut, no fluorescence, and GIA/AGS graded would qualify under this scenario. 

Scenario 2: Both quality and size were important to our clients. Under this option, they were willing to compromise on quality slightly to get a bigger diamond. They would go for a 1.5 carat, SI1/VS2, G/H color, very good to excellent cut, up to medium blue fluorescence, and GIA or AGS graded diamonds. These are still high-quality and premium grade diamonds.

Scenario 3: They were willing to compromise on the 3Cs to get a bigger stone as long as the stone was still eye clean and had enough brilliance. Under this option, they would go for, say, a 2-carat diamond that would be I/J color, SI1/SI2 clarity, up to strong blue fluorescence, very good to ideal proportions, and GIA/AGS graded. If you go for this option, make sure that you understand how to assess the clarity of a diamond well. Some inclusions, such as large black crystals, should be avoided in low clarity grades as they can be visible in SI1/SI2 range if present.

Scenario 4: Our clients would compromise on 1C heavily to maximize the 3Cs. In this case, we recommend that you compromise on the color and prioritize clarity and cut. While you will get a slightly warmer color diamond, it will still have fire and sparkle. A good option would be a VVS2, L, medium to strong blue fluorescence with ideal proportions. You can even go for IGI or HRD grading labs in these ranges since most reputable labs are consistent in grading diamonds with lower quality. It is just that they are inconsistent in grading high quality diamonds as strictly as GIA.

Budgeting for Oval Cut Diamonds:

Below is a list of the suggested carat weight, cut, color, and clarity of Oval Cut Diamonds for people on a tight budget.

Excellent Choice

  • At least 1.2 Carat in Weight
  • Very Good to Excellent Polish and Symmetry
  • G or above in color
  • SI1 or above in clarity
  • No Fluorescence
  • Length/width ratios: 1.36 - 1.58

Very Good Choice:

  • At least 1 Carat in Weight
  • Good to Excellent Polish and Symmetry
  • H or above in Color
  • SI1 or above in Clarity
  • None, faint or medium blue fluorescence
  • Length/width ratios: 1.36 - 1.58

Good Choice:

  • At least 0.90 Carats in Weight
  • Good to Very Good Polish and Symmetry
  • I or above in Color
  • SI1 or above in Clarity
  • None, faint or medium blue fluorescence
  • Length/width ratios: 1.36 - 1.58

Clarifying Key Questions About Oval Cut Diamonds:

Are oval cut diamonds popular?

Yes, after round cut diamonds, oval diamonds have emerged as the most popular shapes lately. They are very popular among shoppers who like round diamonds but want something different.

What about the size of oval cut diamonds compared to round cut diamonds?

Oval cut diamonds have a big surface size. Since they are more elongated, they have a bigger surface size in mm than round diamonds.

Do oval cut diamonds sparkle the same as round diamonds?

While rounds are the king of sparkle and scintillation because of modern cutting techniques, oval cut diamonds are the queen. In our opinion, they stand second in sparkle to round diamonds and have similar brilliant faceting that qualifies the diamond as a modified brilliant cut.

What about the bow-tie effect in oval cut diamonds?

Bow-tie is an issue that can affect oval cut diamonds negatively. Thoroughly read our bow-tie guide and clarify with the retailer about the bow-tie effect before buying an oval cut diamond. If a stone is cut poorly with uneven proportions, it will have a large bow-tie—a sign of a poor cut.

What is the ideal length-to-width ratio for oval cut diamonds?

In our opinion, 1.3 to 1.6 is a good range. Depending on how roundish you want the stone to look, anything between this range will do, though our preferred range is 1.4-1.55.

Check out our loose diamonds page to find recommendations for the best places to buy oval cut diamonds.

Recommended Proportions - Oval
Depth% Table Girdle Cullet L/W Ratio
56-62% 52-63% See Below None