Kimaï
Lab-grown diamonds in recycled gold, sold from a Marylebone shop you can simply walk into, at roughly a third of what the equivalent stone costs on Bond Street. There is a significant returns caveat worth understanding before you commit.
24 Chiltern St, W1U 7QE · View on Google Maps · Visit website · 07897789225
Antwerp Diamond Families, Selling the Other Kind
Kimaï was founded in 2019 by Jessica and Sidney, childhood friends from Antwerp who both grew up in the diamond trade. Her family were traders; his father and grandfather were jewellers, and he holds GIA certification in diamonds and coloured stones. They then built a business selling lab-grown stones exclusively, which given the backgrounds is either ironic or well informed depending on your view.
The pitch is straightforward. A lab-grown diamond is chemically and optically the same material as a mined one, costs considerably less, and lets a given budget buy a noticeably larger or cleaner stone. Everything is set in recycled gold, and they hold B Corp certification. Rings are handmade in Antwerp.
This is the direct opposite of the Hatton Garden and Mayfair model on almost every axis: prices published online, a shop you can walk into on a Tuesday afternoon, and no pretence that the stone is rare.
Two people from Antwerp diamond families decided the interesting business was the one selling stones that are not rare.
London Engagement RingsWalk In, or Commission for £500 Down
You can buy from stock or commission. Existing designs are customisable on cut, carat, shape and band, which covers most people. Full bespoke runs through consultation, sketches, diamond selection with a gemologist against your budget, then making, and requires a £500 deposit that comes off the final invoice.
Production is up to six weeks for bespoke, six to eight weeks for engagement rings generally, and about ten days for ready-to-ship. Stones above 0.5ct carry an IGI, GIA or HRD certificate, and they note they mostly use IGI, with the others available on request for larger stones. Resizing is complimentary on all their engagement rings.
Read this part carefully: all rings, including engagement rings, plus anything engraved or made to order, are final sale and cannot be returned or refunded. That is a materially tighter policy than most of the trade and it applies even to stock designs.
123 Reviews, and a Handful Worth Reading
The distribution is 107 five star against 12 one star, which is a sharper split than most jewellers on this site and worth understanding rather than averaging away. There is no single recurring complaint, so this is not a pattern so much as a scattering.
Of those twelve, the substantive ones describe a diamond coming loose, a bespoke consultation starting late, and two separate accounts of walking into the shop and struggling to get served. Set against 107 five star reviews and 29 in the past year alone, that is a small minority, but the in-store service point comes up more than once and is worth knowing if you plan to arrive unannounced on a Saturday.
Positive themes are thinner here than at bespoke houses, which is what you would expect when a good deal of the business happens online: six reviewers describe the design process, five mention aftercare and resizing, five that their partner loved the ring. They reply to three percent of reviews, effectively none.
Review figures taken from Google and checked in July 2026. We recount them monthly.
The Right Buyer for Kimaï
This suits someone who has decided a lab-grown stone is the sensible choice and wants to get on with it, without a lecture about resale value. Your budget goes considerably further here than anywhere in Mayfair, and the pricing is on the website rather than extracted through an appointment.
It also suits anyone who wants to see rings without booking a private consultation first. Genuine walk-in access to engagement rings is rare in London, and worth something if you are still working out what you like.
It will not suit you if you want a natural stone, if resale or heirloom value matters to you, or if you want the reassurance of being able to return a ring you have changed your mind about. That last point is the one to weigh hardest, because the final sale policy is unusually firm.
The most accessible engagement ring buying in central London: published prices, a walkable shop, B Corp certification and lab-grown stones that make a budget stretch. The trade-offs are real though. Rings are final sale, and a minority of reviewers describe in-store service that did not match the product.
Kimaï: Frequently Asked Questions
How much are Kimaï engagement rings?
They start at £2,320 for the Grace Round, with the Lola Oval at £2,545 and the Jackie Thin Pear at £2,595, rising to around £14,255. Prices are published on the site rather than given only in consultation.
Can I return a Kimaï engagement ring?
No. All rings, including engagement rings, plus engraved and made-to-order pieces, are final sale and cannot be returned or refunded. Resizing is complimentary on their engagement rings, but a change of mind is not covered. This is firmer than most of the trade, so be certain before ordering.
Are Kimaï diamonds real?
They are lab-grown, which means chemically, physically and optically identical to mined diamonds but created in a laboratory rather than found. Stones above 0.5ct come with an IGI, GIA or HRD certificate. They do not sell mined diamonds at all.
Do I need an appointment at Kimaï?
No, the Marylebone shop takes walk-ins Tuesday to Saturday, 10am to 6pm. Weekdays are easier for engagement rings; Saturdays get busy with booked bridal appointments, so book ahead if that is your only option.
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