Oval Diamond Ratio, Sizes and Price
By Jared James · Last updated 28 October 2026
Quick answer
An oval diamond gives you a larger, more lengthening look than a round diamond of a similar weight, and it keeps the bright sparkle pattern of a brilliant cut. There is no single cut grade that tells you whether an oval is a good one, so the things to look at are the bow tie, the length-to-width ratio, the shape of the shoulders and how evenly the two ends mirror each other.
Shape at a glance
| Detail | Typical detail | Buying note |
|---|---|---|
| Facet pattern | Modified brilliant, usually with 56 to 58 facets. | You can expect bright brilliant-cut sparkle, but judge each stone on its own because oval quality varies a lot. |
| Typical ratio | Around 1.35 to 1.50; our ovals have a typical ratio of 1.43. | Lower ratios look fuller and rounder, while higher ratios look longer and more slender. |
| Sparkle | Bright and lively when cut well, with possible bow tie through the centre. | A slight bow tie is normal, so just avoid any stone where the dark band takes over the centre. |
| Best for | Solitaire rings, hidden halos, three-stone rings and elongated hand proportions. | Choose oval when you want presence and length without moving to a sharp-cornered shape. |
What is an Oval Cut Diamond?
An oval diamond is an elongated brilliant cut, which means it takes the light-return geometry of a round brilliant and stretches it into a longer outline, and that extra length is what makes an oval look larger from above than a round of the same carat weight.
It has become one of the most popular shapes for engagement rings because it flatters the hand, sits comfortably in both plain and detailed settings, and keeps a softer outline than the pointed marquise or pear.
What is the best ratio for an oval diamond?
Between 1.35 and 1.50 for the classic oval, and 94% of the ovals on our builder sit in that range, with a typical ratio of 1.43. The ratio is the length divided by the width, so a 1.43 oval is a little under one and a half times as long as it is wide.
Below about 1.35 an oval looks fuller and closer to round; above 1.50 it looks longer and slimmer. Choose by the look you like on the hand, and we can filter our stones to the ratio you want.
What size is an oval diamond at each carat weight?
A 1 carat oval measures about 8.2 by 5.7 mm and a 2 carat about 10.3 by 7.2 mm. These are the typical sizes of the IGI-graded ovals on our builder, measured stones rather than a formula.
Length is what you notice on the hand: a 1 carat oval is about 8.2 mm long, against 6.5 mm across for a 1 carat round, which is why ovals look larger for their weight.
| Carat weight | Typical size (mm) | Typical ratio (middle 80%) |
|---|---|---|
| 1 carat | 8.2 x 5.7 | 1.43 (1.39 to 1.48) |
| 1.5 carat | 9.3 x 6.5 | 1.42 (1.38 to 1.47) |
| 2 carat | 10.3 x 7.2 | 1.44 (1.39 to 1.47) |
| 2.5 carat | 11.0 x 7.7 | 1.43 (1.39 to 1.48) |
| 3 carat | 11.8 x 8.2 | 1.43 (1.39 to 1.47) |
| 4 carat | 12.8 x 8.9 | 1.42 (1.40 to 1.50) |
Measured from the IGI-graded oval lab-grown diamonds on our builder feed on 28 October 2026, each weight band running to .09 of a carat (1 carat means 1.00 to 1.09 ct). Typical is the median stone.
How much does an oval lab-grown diamond cost?
About $1,340 at 1 carat and $2,440 at 2 carats on our builder, and a complete 18k gold oval ring starts at $3,300. Every stone we sell is graded by IGI at D to F colour and VS1 clarity or better.
At 1 carat an oval costs a little more than a round, a median $1,335 against $1,242. At 2 and 3 carats our complete oval rings start lower than our round ones.
| Carat weight | Typical loose stone | Most stones (middle 80%) | Complete 18k gold ring |
|---|---|---|---|
| 1 carat | $1,335 | $1,284 to $1,558 | $3,300 to $4,350 |
| 1.5 carat | $2,117 | $1,671 to $2,233 | $3,800 to $4,200 |
| 2 carat | $2,436 | $2,267 to $2,800 | $4,500 to $5,500 |
| 2.5 carat | $2,822 | $2,337 to $4,112 | $6,550 to $6,950 |
| 3 carat | $3,850 | $3,215 to $5,063 | $6,900 to $7,900 |
| 4 carat | $6,828 | $3,833 to $8,910 | $9,450 to $9,800 |
Loose stone prices from our builder feed and complete ring prices from our carat collections, 18k gold, checked 28 October 2026. Rings at other weights are made to order: choose the stone and setting in our ring builder.
What to check before choosing
Check the bow tie
Almost every oval shows some shadow across its centre, and a soft, balanced bow tie that flickers as the stone moves is completely normal. What you want to avoid is a dark band that stays put and dull no matter how the diamond catches the light.
Choose the ratio by hand feel
A fuller oval feels classic and soft, while a longer one feels more dramatic, so the ratio that suits you really comes down to your finger length, the width of the band and the setting you have in mind.
Look closely at symmetry
Both ends of the oval should mirror each other and the shoulders should curve smoothly into the tips, because uneven shoulders or a slightly off-centre point are much easier to notice once the stone is set in a ring.
1.36 ratio
A fuller oval, 8.9 by 6.5 mm.
1.43 ratio
Our typical ratio, 9.3 by 6.5 mm.
1.54 ratio
A longer, slimmer oval, 8.8 by 5.8 mm.
Settings that suit this shape
- A north-south solitaire, with the oval running along the finger, lengthens the hand and keeps all the attention on the stone.
- Turning the oval east-west, so it sits across the finger, gives the ring a more contemporary look and a lower profile.
- A hidden halo or a few delicate side stones add detail and a little extra sparkle without changing the clean oval outline too much.
Who does oval suit?
Oval suits anyone who wants a centre stone that looks generous for its weight, a graceful outline and plenty of sparkle. It works best when the ring design stays simple enough to let the shape itself carry the look.
Watch for
- A strong bow tie can leave the centre of the stone looking dull and shadowed.
- A very elongated oval can show a little more colour at its rounded tips.
- A narrow band makes the oval look larger, though it still needs enough metal in it to stand up to daily wear.
Watch: 4 facts before you buy an oval diamond
A quick run through four things worth checking before you choose an oval cut diamond.
Frequently asked questions
- What is the best oval diamond ratio?
- Between 1.35 and 1.50 for the classic oval. 94% of the ovals on our builder sit there, with a typical ratio of 1.43; below 1.35 looks fuller, above 1.50 longer and slimmer.
- What does a 1.45 ratio oval look like?
- A classic, balanced oval, a little under one and a half times as long as it is wide. On a 1 carat stone that is about 8.3 by 5.7 mm.
- How big is a 1 carat oval diamond?
- About 8.2 by 5.7 mm, measured on the oval lab-grown diamonds on our builder, against 6.5 mm across for a 1 carat round.
- Is an oval cut diamond more expensive than a round?
- A little, at 1 carat on our builder: a median $1,335 against $1,242 for a round (28 October 2026). At 2 and 3 carats our complete oval rings start lower than our round ones.
- Do all oval diamonds have a bow tie?
- Most ovals show some bow tie, so the aim is a soft shadow that moves and flickers with the stone rather than a dark band that sits over the centre and stays there.
- Are oval diamonds good for engagement rings?
- Yes. They are bright and flattering on the hand, and with a rounded outline there are no points to chip. Look for good symmetry and a balanced bow tie.
