Oval diamonds are one of the most popular fancy shapes in the world, combining the brilliance of a round cut with an elongated silhouette that flatters the hand. While ovals are often praised for appearing larger than their carat weight, they are also one of the most visually inconsistent shapes to buy. Two ovals with identical carat, color and clarity can look very different in person.
This guide explains how oval diamonds work, what matters most when choosing one, and how to avoid the mistakes that cause buyers to end up with a less brilliant stone than expected.
Why Oval Diamonds Are Popular
Oval diamonds are valued for three qualities: strong brilliance, an elegant elongated outline, and a face-up appearance that looks larger than the carat weight suggests.
Because an oval spreads its weight along its length rather than concentrating it in a circle, it covers more of the finger than a round diamond of equal carat. This gives buyers more visual size without increasing the carat weight, and it is one of the main reasons ovals are chosen over rounds at a similar budget.
The elongated outline also has a lengthening effect on the finger, which is part of why ovals are common in solitaire, hidden halo, three-stone and east-west settings.
A beautiful oval cannot be selected from specifications alone. Shape, symmetry and bow-tie visibility need to be assessed visually before a stone is purchased.
A Brief History of the Oval Diamond
Elongated brilliant shapes have existed in some form for centuries, but the modern oval brilliant cut is credited to Lazare Kaplan, a diamond cutter from a family recognised for expertise in cleaving and cutting important stones.
Kaplan developed the modern oval brilliant in 1957, adapting the faceting structure of the round brilliant into an elongated shape, typically built on 57 or 58 facets. This gave the oval its modern identity as a diamond carrying much of the brilliance of a round cut, set within a softer, elongated outline.
What Makes an Oval Diamond Different
Oval diamonds are often brilliant-cut diamonds, meaning their facets are arranged to maximise light return, sparkle and contrast, rather than producing the broad, mirror-like flashes seen in step cuts such as emerald or Asscher diamonds. Ovals can also be found as step cut-diamonds, but those are less common.
A standard oval brilliant has:
- 57 facets if there is no culet
- 58 facets if a culet is present
- Brilliant-style faceting across the crown and pavilion
- An elongated outline with two rounded ends
An oval can be thought of as an elongated round brilliant, but it does not behave like one. Round diamonds follow a highly standardised shape, which allows laboratories to grade cut quality consistently. Oval diamonds vary far more in outline, proportions and facet arrangement, which means two ovals with similar certificate details can still look very different. This is why visual assessment matters more for ovals than for round diamonds.
Does an Oval Sparkle as Much as a Round Diamond?
A well-cut oval can be bright and lively, but round diamonds still have the advantage for pure light performance. The reason is geometry: a round brilliant has a symmetrical outline and a facet pattern engineered specifically for maximum light return. Stretching that pattern into an oval introduces more variation in how light travels through the stone.
A good oval should show:
- Bright, even light return
- Sparkle across the full stone
- Minimal darkness through the centre
- A balanced outline
- No distracting bow-tie
A poorly cut oval may look dull in parts, overly dark across the middle, or uneven from one end to the other.
For buyers comparing the two shapes: round diamonds are usually the safer choice for maximum sparkle, while oval diamonds offer more shape, elegance and face-up presence. The right choice depends on what the buyer values most.
The Bow-Tie Effect Explained
The bow-tie effect is one of the most important factors to check in an oval diamond. It is a dark shadow across the centre of the stone, often appearing as two dark triangular areas meeting in the middle.
(The image shows a diamond with minimal to no bow-tie, next to one with a bow-tie)
Most oval diamonds show some degree of bow-tie. A slight bow-tie is normal and can add contrast and depth. A strong bow-tie can make the diamond look dark, flat or poorly cut.
What causes a bow-tie?
A bow-tie occurs when facets reflect the viewer, their camera, or their surroundings instead of returning light from the environment. Bow-tie strength is influenced by:
- Facet alignment
- Pavilion depth
- Overall proportions
- Length-to-width (LW) ratio
- How the diamond is filmed or viewed
Longer ovals are more prone to visible bow-tie, but ratio alone does not determine severity.
How to assess bow-tie in video
A good oval will show some contrast, but the dark area should shift, break up and flash as the stone turns. A poor oval will show a dark, static band across the centre that remains visible from multiple angles. Look for brightness across the belly of the stone, movement through the centre, and no permanent black band. A certificate cannot show this. It should be assessed through 360 video or tweezer videos.
Ideal Oval Diamond Proportions
Like round diamonds, IGI gives oval diamonds a cut grade. This is, however, not the case for GIA yet, although they will implement fancy cut grades in 2027. Due to less standardisation of fancy cuts, buyers cannot rely on a single grade in the way they might for a round brilliant. Instead, proportions, symmetry and visual performance need to be considered together. The ranges below are useful starting points, and not strict rules. The following ranges are based on IGI’s definition of an excellent cut, with some descriptions of the more commonly discussed properties.
Length-to-Width (LW) Ratio
Calculated by dividing the diamond's length by its width. A diamond measuring 9.00mm long and 6.00mm wide has a ratio of 1.50.
1.20–1.29: short and rounded, sometimes close to a round or cushion-like appearance
1.30-1.39: soft, slightly rounded oval
1.40-1.49: classic oval shape
1.50-1.55: longer, more elongated oval
Above 1.55: very elongated and dramatic
IGI suggests an excellent cut oval is in the L/W ratio to be between 1.35–1.50. However, for a buyer the ratio can also be a style decision.
Depth Percentage
Depth: 58-63%
Very deep ovals can hide weight in the pavilion and look smaller than their carat weight suggests. Very shallow ovals may struggle with light return and show watery or glassy areas.
Table Percentage
Table: 56-62%
A very large table can make the diamond look flatter and reduce fire. A very small table can affect the balance of brightness and pattern.
IGI’s definition of an excellent cut oval in full
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Why Oval Diamonds Look Larger Than Their Carat Weight
Carat measures weight, not visible size. Because an oval's weight is spread across a longer shape, it offers more finger coverage and a larger visual outline than a round diamond of equal carat.
For example, a 1.00 carat round diamond is typically around 6.4–6.5mm in diameter, while a 1.00 carat oval might measure around 7.7mm by 5.7mm, depending on proportions. This is one of the main reasons buyers choose ovals: stronger visual presence without increasing carat weight. However, a deep oval can still look smaller than expected if the proportions are not well balanced.
Color in Oval Diamonds
Oval diamonds can show color more readily than round diamonds. Round brilliants mask warmth effectively because their faceting returns light evenly across the stone. Ovals still have brilliant faceting, but their elongated shape can concentrate color toward the ends, most noticeably in larger stones and in white metal settings.
D–F: colorless, best for buyers who want a very white appearance
G–H: often the best balance for white gold or platinum
I–J: can still look beautiful, especially in yellow or rose gold
K and below: warmth is more likely to be visible, particularly in larger stones
For most engagement rings in white gold or platinum, G–H offers strong value. For yellow gold, slightly warmer colors can look soft and harmonious.
Clarity in Oval Diamonds
Oval diamonds hide inclusions reasonably well due to their brilliant faceting. For most buyers, VS2 is a sensible clarity target. A carefully selected SI1 can also be eye-clean, particularly in smaller stones, though it requires closer inspection. Higher grades such as VVS or IF rarely improve visible appearance.
Buyers should look carefully at:
- Inclusions in the centre of the stone
- Dark crystals under the table
- Large feathers near the girdle
- Inclusions that reflect multiple times
- Inclusions near areas where the bow-tie is already visible
Inclusions near the edges are easier to hide under facets or prongs, while inclusions in the open centre are more visible because the eye is naturally drawn there.
Symmetry and Shape Balance
Symmetry is one of the most important factors in an oval diamond. A well-shaped oval should feel balanced from every angle, with both ends mirroring each other and smoothly curving shoulders.
Look for:
- Even shoulders on both sides
- Matching ends
- A centred culet
- Smooth curves
- No flat sides or bulging shoulders
- No twisted or uneven outline
Poorly shaped ovals can look slightly uneven, with one side sitting higher than the other or an outline that resembles a rounded rectangle or marquise. A high-quality certificate does not guarantee a beautiful outline, so the face-up shape should always be reviewed before focusing on the 4Cs.
Lab Grown vs Natural Oval Diamonds
Lab grown and natural oval diamonds are optically and chemically identical. The difference lies in origin: natural diamonds formed in the earth over millions of years, while lab grown diamonds are created in controlled environments using modern technology.
For oval diamonds, the buying considerations are the same regardless of origin:
- Bow-tie still matters
- Symmetry still matters
- Color and clarity still matter
- Video inspection is still essential
Lab grown oval diamonds are widely available and most commonly graded by IGI. While both GIA and IGI grading is common for natural oval diamonds, the choice of laboratory can vary by supplier. Lab grown ovals are typically priced significantly lower than natural diamonds of equivalent visible size and quality, which often allows buyers to choose a larger stone, a higher color grade, or a more carefully selected diamond within the same budget.
Common Mistakes Buyers Make With Oval Diamonds
- Choosing by certificate alone, without reviewing video or images
- Ignoring or underestimating bow-tie severity
- Selecting a length-to-width ratio that does not suit their hand or setting
- Overpaying for clarity grades that offer no visible improvement
- Overlooking symmetry issues such as uneven shoulders or mismatched ends
- Assuming every oval will look larger than its carat weight, regardless of proportions
How to Choose an Oval Diamond Using Carateu
Carateu allows you to compare oval diamonds transparently using filters for proportions, symmetry, clarity and certification. For oval diamonds, this is especially important, since the details that matter most are visual rather than purely numerical.
All diamonds are:
- IGI or GIA certified
- Verified by a gemologist in Sweden
- Shipped within the EU with VAT included
- Priced with no hidden fees
You can explore available stones directly on our Lab Grown Oval Cut Diamonds or Natural Oval Cut Diamonds pages.
If you can't find what you want or need some advice on your diamonds, you can reach out directly to Carateu's gemologist through the Carateu's Concierge service.
Final Checklist Before You Buy a Pear Diamond
- Choose a length-to-width ratio that suits your style
- Review video for bow-tie severity and movement
- Prioritise excellent or very good symmetry
- Select VS2+ clarity for a clean look
- Pick a color grade that suits your setting metal
- Confirm strong polish and a trusted grading report
- Check the face-up outline before focusing on the 4Cs
Frequently Asked Questions
Are lab grown oval diamonds real diamonds?
Yes. Lab grown oval diamonds are real diamonds with the same chemical, physical and optical properties as mined diamonds. The only difference is how they are formed.
Why do oval diamonds look larger than their carat weight?
Oval diamonds often appear larger than round diamonds of the same carat because their elongated shape spreads weight across more surface area, increasing finger coverage and visible size.
What is the bow-tie effect in oval diamonds?
The bow-tie effect is a dark shadow that can appear across the centre of an oval diamond when facets reflect the viewer instead of returning light from the surroundings. A slight bow-tie is normal, but a strong, static bow-tie indicates poorer light performance.
What is the best length-to-width ratio for an oval diamond?
Most buyers are well served by a ratio between 1.35 and 1.50. Lower ratios appear shorter and rounder, while higher ratios create a longer, more dramatic outline.
Are lab grown oval diamonds more affordable than natural diamonds?
Yes. Lab grown oval diamonds are typically priced significantly lower than natural diamonds of equivalent visible size and quality, while offering the same optical appearance.
Final note: buyers comparing oval, round and pear shapes may also find our round diamond buyer's guide and pear diamond buyer's guide helpful.
