0.4 Carat Diamond Engagement Rings

Create your dream 0.4 carat diamond ring. Start by finding your design with our collection of rings, each created to enhance the beauty of your gemstone, then complete with the diamond of your choice.

Most rings shown with 1 ct diamond

We’re here to help

We get it, you’ve never done this before.

That’s why we have diamond and design experts on hand, who are here to guide you through every step - from understanding what carat, color, cut and clarity mean, to designing the perfect ring.

About 0.4 ct diamond rings

Weighing just a little less than a half carat, a 0.4 ct diamond equates to 0.8mg and a round shape typically measures 4.80mm in diameter. A 0.4 carat engagement ring is on the smaller side, and is now far less common than it once was. Thanks to the emergence of lab diamonds, most couples now choose a larger carat weight. That said, a 0.4 carat diamond ring is the perfect choice for those that like an understated jewellery look.

A 0.4 ct diamond can be enhanced with a halo ring design or kept simple with a plain solitaire band. Our experts advise avoiding fussy or complex designs, and instead letting your diamond do all the talking.

Ring Styles

Modern classics

You want your ring design to be timeless, and we get that. Our collection features rings that transcend trends, look great from every angle and are made to last a lifetime.

Try filtering your search by our core engagement ring styles:

Solitaire engagement rings
Diamond band engagement rings
Halo engagement ring
Trilogy engagement rings

Our Diamonds

Ethically sourced & certified

The modern way to buy loose diamonds for your engagement ring, with real 360 videos and advanced filtering. Whether you're looking for a lab-created or natural centre stone, find the perfect loose diamond from our responsibly sourced collection of certified diamonds.

Exquisite Craftsmanship

Made for you

Each Queensmith engagement ring is crafted to order, made just for you and your partner. We have an in-house workshop and production team that meticulously crafts your ring and finesses every detail until it passes our final quality control check. Our quality and finish is a cut above the rest.

As part of our commitment to you, we offer a Lifetime Care Package including manufacturer's warranty, free servicing, free resizing and free cleaning, fully inclusive with every ring made by us.

We've Got You Covered

In London
Certified Diamonds
Free UK
Free Resizing
40 Days

Frequently Asked Questions

Learn About 0.4 ct Diamond Rings

Is a 0.4 carat diamond ring a good choice?

Absolutely - a 0.4 carat diamond can be a great choice! If you’re after a dainty-looking diamond engagement ring, then any diamond below 0.5 carat will give you that understated look.

How much does a 0.4 ct diamond ring cost?

The price of a 0.4 carat engagement ring starts around £1,400 for a lab diamond ring. The cost of a loose 0.4 ct lab diamond starts at £650, or £1,100 for a natural diamond. In addition to this, the price of the ring itself starts at £700.

You should be aware that diamond prices fluctuate, and this should be used as a guide price accurate at the time of writing.

Is 0.4 ct too small for an engagement ring?

No, 0.4 ct is a good weight for an engagement ring. The lowest carat weight you should consider for your ring is 0.3 ct - any smaller and you might have to compromise on the design. A 0.4 ct diamond isn’t huge, but it will still offer gorgeous sparkle and radiance so long as you choose a gem with top cut, colour and a decent clarity grade.

How big is a 0.4 carat diamond ring?

A 0.4 carat round diamond will measure approximately 4.80mm in diameter, but this will vary a little depending on how well the diamond has been cut. Other shapes of the same carat weight can appear much larger - for example, a 0.4 ct oval diamond could be closer to 5mm in length.

Customer Support

Do you have additional questions? No problem, let us help you through the process

Need help choosing the perfect ring?

Get in touch with our experts - we’re on hand to help.

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