Oval Engagement Rings
An oval looks larger than a round of the same carat weight and costs less per carat.
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Engagement rings / Round
Is a round engagement ring right for you?
Round is still the most popular shape for a reason: no other diamond sparkles as much. It costs the most per carat, but it’s also the shape that hides colour and small marks best. Here’s how to get the most from it.
PK
Parth KananiOctober 2026 · 6 min read
In short: Round gives you the most sparkle and never dates. It costs more per carat than any other shape. Insist on an Excellent cut grade, then save on colour and clarity, because round hides both better than any other shape. A 1ct round solitaire in 18ct white gold costs about £3,900–£5,600 natural, or £1,650–£2,850 lab-grown.
Size
How big does a round diamond look?
Carat is weight, not size. Here's a 1ct round drawn to scale against a 1ct round, and what each weight measures from above.
| Carat | Typical size |
|---|---|
| 0.5ct | 5.1mm |
| 0.7ct | 5.7mm |
| 1.0ct | 6.4mm |
| 1.5ct | 7.3mm |
| 2.0ct | 8.1mm |
Length-to-width ratio: 1.00. A round should be round. The certificate shows minimum and maximum diameter, and they should be within a few hundredths of a millimetre.
Prices
What a round engagement ring costs in Hatton Garden
A solitaire in 18ct white gold with a certified G colour, VS2 clarity, well-cut round diamond. Prices include the setting.
| Carat | Natural diamond | Lab-grown diamond |
|---|---|---|
| 0.5ct | £1,600–£2,400 | £800–£1,400 |
| 0.7ct | £2,400–£3,600 | £1,100–£1,950 |
| 1.0ct | £3,900–£5,600 | £1,650–£2,850 |
| 1.5ct | £7,400–£10,600 | £2,850–£5,100 |
| 2.0ct | £12,400–£18,600 | £4,600–£8,700 |
Why G and VS2? Round hides colour and inclusions better than any other shape. G colour and VS2 clarity look perfect to the eye; you can often go to H and SI1 if the stone is clean to look at.
Platinum adds roughly £200–£300 to the setting. Lab-grown diamonds look identical but resell for much less. Our lab-grown vs natural guide covers the trade-off.
On the hand
What you'll actually see
A 1ct round is about 6.4mm across. It looks the same from every angle and suits every hand.
It has the brightest, most even sparkle of any shape, with no dark bow-tie.
Because it sparkles so much, small marks and slight colour are hard to see.
A round suits you if…
- Sparkle is what you want most from a diamond
- You want a ring that will look as right in 30 years as it does now
- You aren’t sure what they’d like. Round is the safest choice
Think twice if…
- You want the most visual size for your spend. Oval looks bigger for less
- You want something less common
Before you buy
What to check on a round diamond
- 1Insist on an Excellent cut grade. Round is the only shape with an official cut grade from GIA and IGI, so use it.
- 2Ask for a stone that is “eye-clean”: no marks you can see without magnification. SI1 rounds often are.
- 3Compare two stones of the same grade side by side. Small differences in proportion change how much they sparkle.
Every diamond should come with a GIA or IGI report. Here's how to read one in 30 seconds.
Settings
The settings that suit a round best
Solitaire
The classic: four or six claws holding one round diamond.
Halo
Makes a round look bigger by surrounding it with small diamonds.
Three-stone
A round centre with two smaller stones. More presence without a bigger centre.
Where to look
Seeing round diamonds in Hatton Garden
Shape is the one thing you can't judge from a certificate, so you need to see real stones. A traditional shop window might hold a handful of rounds. Online-first jewellers give you thousands of certified round diamonds to filter by size, ratio and price before you book a viewing, so your visit is for choosing, not searching.
MOH London's certified diamond search is a good place to start: filter for round, compare certified stones side by side, then see your shortlist at their Hatton Garden consultation suite. Or compare every option in our independent jeweller reviews.
Not sure yet? Compare other shapes
Or see every shape side by side in our diamond shapes guide.
Common Questions
How much does a 1 carat round engagement ring cost?+
In Hatton Garden, a 1ct round solitaire in 18ct white gold typically costs £3,900–£5,600 with a natural diamond, or £1,650–£2,850 with a lab-grown diamond. That’s for G colour, VS2 clarity and a well-cut, certified stone.
How big is a 1 carat round diamond?+
About 6.4mm from above, for a stone of typical proportions. A 1 carat round is about 6.4mm across.
Why are round diamonds more expensive?+
More of the rough crystal is cut away to make a round than any other shape, and demand is the highest. Together, that makes round the most expensive shape per carat.
What cut grade should a round diamond be?+
Excellent (GIA) or Ideal/Excellent (IGI). Cut has more effect on sparkle than colour or clarity, and round is the only shape where you get an official cut grade.