Oval Cut Diamonds | Cut Guide & Ideal Proportions Chart

Oval Cut Diamonds | Cut Guide & Ideal Proportions Chart

Oval Cut Diamonds | Cut Guide & Ideal Proportions Chart

Posted by Sharif Khan on 3rd Jul 2018

Complete Oval Cut Diamond Buying Guide 

Oval cut diamond ring

Bottom Line Recommendation...

  • According to Blue Nile and James Allen (two of our favorite online retailers), oval shape diamonds are taking the number two spot in terms of demand in 2019, right next to the traditional round cut diamonds. They serve as beautiful alternatives to rounds and combines the brilliance of round with marquise cut. Oval cut diamonds also have amazing spread and surface size (they look big). 
  • In terms of cut, a depth of 55-65% and a table of 52-65% is preferred. Follow our chart below carefully while analyzing the cut of oval shape diamonds.
  • Bow-tie is an important topic to be familiar with, and if an oval cut diamond is poorly cut, it will have a large bow-tie effect. Read our guidance below and make sure you have high quality images/videos of the diamond to assess its bow-tie effect carefully before placing an order. 
  • In terms of length-to-width ratio, oval cut diamonds in the range of 1.38%-1.55% are preferred, depending on how roundish or elongated you want the diamond to look. See the chart below for details. 
  • In terms of concrete options, if you don't have budget problems and want a stone of investment grade, look for something like this (option 1). If you want to maximize carat weight within your budget without compromising on quality either, look for an oval cut diamond within this range (option 2). If you don't mind compromising more on the other 3Cs (Cut, Color, Clarity) in order to maximize on 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 in order to maximize on the other 3Cs, compromise on color and maximize on clarity and cut (option 4). 
  • Always buy a diamond that is either graded by GIA or AGS. Here is list of our top online retailers for diamond and engagement rings to consider while shopping. 
  • Here is a list of our top vendors for loose diamonds and engagement rings to consider.

Overview... 

Oval Cut diamond was created by Lazare Kaplan in the 1960's. These luminous gems are different from your day to day diamond shapes as they combine the sparkle of the elongated shape of a marquise cut with the round cut. The shape is cut into a perfectly symmetrical design. Oval cut diamonds possess the fire and brilliance of a round cut diamond which makes it an ideal choice for individuals that like round diamonds, but want something distinct. 

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

The ‘bow-tie effect’ is present in almost all oval, marquis and pear cut diamonds. Since it is an important factor 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 the poor cut of the diamond.

Analyzing Cut -  ideal proportions...

Hint: Use tools like Jame Allen's Video 3D 360 Degree 40X Magnified Technology to compare different diamonds and get sense of what the proportions does to the cut and shape of a diamond. It can especially be helpful in figuring out what might be optimal length to width ratio for you. 

Depth %
  • Poor/Far: <51 or >75/ 70.9-75
  • Good: 54-56.3 / 66-70.8
  • Very Good: 56-58.1/62-65.9
  • Excellent: 57-61.9
  • Table %
  • Poor/Far: <51 or >72 / 70-72
  • Good: 50 / 66-69
  • Very Good: 52/65
  • Excellent: 53-64
  • Culet
  • Poor/Fair: Very Large/Large
  • Good: Slightly large
  • Very Good: Medium/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
  • Poor/Fair: >1.66 /1.62-1.66
  • Good: 1.57-1.61
  • Very Good: 1.51-1.56
  • Excellent: 1.36-1.50
  • James Allen

    The chart above serves as a general guideline when evaluating the cut of an oval cut diamond. The length to width ratio of 1.50 is considered the classic cut for an oval cut diamond. Every Petra Gems diamond includes precise measurements and length to width ratio, so our customers could make a rational decision when considering an oval cut diamond.

    Blue Nile

    Evaluating Color...

    Just like evaluating the color in other diamond shapes, color in an oval cut diamond is also subjective. Our experience indicates many buyers prefer the warmer colors over the cool colors. In the color spectrum, the warmer colors refer to G-I diamonds while the cool colors refer to D-F diamonds. The good side to that is the price premium for a lower color grade oval cut diamond would be lower.

    For more detailed information on the color of an oval cut diamond, 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
  • 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
  • Flouro
  • Poor/Fair: Very Strong
  • Good: Strong
  • Very Good: Slightly Medium
  • Excellent: None
  • Oval Cut Diamond Guide

    Ideal Length to Width Ratio of 1.45

    Choosing Clarity...

    Choose an oval cut diamond that meets your standards in terms of clarity. Each of our customers has a unique standard for clarity and color. Some of our customers want a flawless diamond with a lot of clarity, while others are perfectly comfortable with a slight inclusion as long as it is not easily noticed. GIA provides excellent help with their clarity grades, so you can use it to choose an oval cut diamond that will meet your standards. The chart below serves as a general guide for you to evaluate 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...

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

    Scenario 1: quality was the main concern to them. In this option, they went for the best of the 4Cs in each given carat weight range. Any diamond above 1 carat, F, VS1, excellent cut, no fluorescence, GIA/AGS graded would qualify under this scenario (we call these investment grade diamonds). 

    Scenario 2: both quality and size were important to them. Under this option, they were willing to compromise on quality slightly in order to get a bigger diamond. So instead they would go for something like a 1.5 carat, SI1/VS2, G/H color, very good to excellent cut, up to medium blue fluorescence, and GIA and AGS graded diamond (these are still high quality diamonds and would qualify in the investment grade range). 

    Scenario 3: they were willing to compromise on the 3Cs in order to get a bigger stone as long as the stone was still eye clean and had adequate 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, and very good to ideal proportions, and GIA/AGS graded. If you go for this option, make sure you understand the clarity of the diamond well. Some inclusions such as large black crystals should be avoided in low clarity grades as they can be visible in SI2 if present. 

    Scenario 4: they would compromise on 1C heavily in order to maximize on the 3Cs. In this case, we recommend you compromise on the color in order to maximize on the clarity and cut. While you might get a slightly warmer color stone, 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 labs in this range as most labs in lower color quality stones are consistent in grading diamonds properly. It is just that they are not consistent in grading high clarity grades as strict as GIA. 

    Suggested carat weight, cut, color and clarity of Oval Cut Diamond for people with budget constraints...

    Excellent Choice

    • At least 1.0 carats in Weight
    • Very Good to Excellent Polish and Symmetry
    • G or above in color
    • SI1 or above in clarity
    • No Florescence
    • Length/width ratios: 1.36 - 1.58

    Very Good Choice:

    • At least 0.90 carats in Weight
    • Good to Excellent Polish and Symmetry
    • H or above in Color
    • SI1 or above in Clarity
    • None, faint or medium blue florescence
    • Length/width ratios: 1.36 - 1.58

    Good Choice:

    • At least 0.80 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 florescence
    • Length/width ratios: 1.36 - 1.58

    Frequently Asked Questions About Oval Cut Diamonds...

    Are oval cut diamonds popular?

    Yes, after round cut diamonds, oval diamonds are the most popular shapes lately. They very popular among shoppers that 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 just like round diamonds. Since they more rectangular than square, they might even have a bigger surface size in mm than rounds. 

    Do oval cut diamonds sparkle the same as round diamonds?

    While rounds are the king of sparkle and scintillation simply because of the advancement of cutting techniques for round shape diamonds, ovals are the queen. They are the second in our opinion that have similar brilliant faceting to maximize sparkle and fire, combing the best of marquise and round diamonds. 

    What about bow-tie effect in oval cut diamonds?

    Bow-tie is an issue that can affect oval cut diamonds. Make sure you read our bow-tie guide and consult the diamond dealer before buying the stone about the bow-tie effect. If a stone is badly cut with uneven proportions, it will have a bow-tie - a sign of a poor cut. 

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

    In our opinion anything between 1.3 to 1.6 is a good range depending on how roundish you want the stone to look. Our preferred range is 1.38-1.55.

    Be sure to check out our loose diamonds page to find recommendations for best places to buy oval cut diamonds.