I’ve worked with UNDONE a few times now, and they were actually one of the first brands I featured on this blog. They’ve always been known for their highly customizable watches, with some fun limited editions thrown in along the way. But now they’re stepping into the integrated bracelet market with a lineup that honestly surprised me when I first heard about it.
After actually getting the watch on my wrist though? I completely get it.
This is my full review of the UNDONE Slim.
The Brand
UNDONE is a brand I genuinely enjoy. They offer a wide range of customizable watches depending on the model, and they’ve done some really cool collaborations and limited editions over the years. Customer service has been great in my experience, and the pricing is quite reasonable when you factor in the specs, materials, and level of customizability on offer.
Packaging
The UNDONE Slim comes in pretty straightforward packaging. A black box with a magnetic-sealed threefold lever. Nothing I’d put on a shelf to show off, but it’s solid protection and definitely better than some other brands in this space.
At this price point, I’d rather the money go into the watch itself anyway, and that’s exactly what feels like happened here.
Design
Let’s talk about the design. There’s nothing that’ll blow your mind at first glance, and honestly, as the name suggests, the slimness of the watch is the main attraction. But what an attraction it is.
I chose to review the gray dial version specifically because it blends beautifully with the metallic case and bracelet, giving it an almost bracelet-like feel when worn. It’s subtle, and I know that’s not for everyone, but it’s exactly why I love this version.
On the wrist, this thing almost looks like a piece of jewelry from certain angles. As watch enthusiasts, we rarely get to experience wearing something this slim, because ultra-thin mechanical watches tend to live in the six-figure territory (think the Bulgari Octo Finissimo). So getting that sensation at this price point is genuinely exciting.
The keyword for the design of the Slim is light play. Everything on this watch is designed to catch and reflect light in interesting ways. The dial features a sharp sunburst finish, with raised hour markers that have subtly tapered tops giving them more facets to work with. The hands are beautifully sculpted sword-style with a triangular raised ridge running through the centre. The beveled case edges, though slim, catch your eye as you move your wrist. And the bracelet, with its flat wide H-segments alternating with square centre links, shifts and flickers with every turn of your wrist.
I also love the minimal text on the dial. No water resistance spec cluttering things up. And placing the UNDONE logo at 6 o’clock is a fun, slightly unexpected touch. First time I opened the box, it genuinely made me smile, almost like wearing the watch upside down.
One small thing I’d consider: given how dressy and slim the whole piece feels, a slightly narrower case profile tapering more aggressively into the bracelet could elevate it further into real dress watch territory. But that would require sacrificing some of the sporty character, so I understand why they kept it where they did.
Design Conclusion
Overall, the UNDONE Slim is a well-thought-out design. Nothing is left to chance. At first glance it may read as a bit generic, but the combination of its slim profile, integrated metal bracelet, polished beveled angles, and that cheeky dial placement gives it a cool and coherent identity that grows on you fast.
Quality
For the price, the quality here is genuinely impressive. And importantly, you have to factor in the engineering challenges that come with making something this slim. Thinness costs money, and that context matters when you’re evaluating what you’re getting.
Case, Bezel and Crown
Both the case and bezel are extremely thin, and yet UNDONE didn’t stop there. They added polished beveled edges with clean, well-defined borders between the brushed and polished surfaces. The finishing isn’t flawless up close, but it’s very solid and consistent for this price bracket.
The crown has a lovely hexagonal shape with an embossed logo that looks almost welded on. No cheap laser engraving here. It’s a small detail, but it matters.
Worth noting: the crown is slightly thicker than the case itself, so it protrudes a touch at the right angle. That said, making it any smaller would make it fiddly to use, so it’s a reasonable trade-off.
Dial and Hands
Simple in concept, but executed with tight tolerances given how slim everything needs to be.
Everything is perfectly centred. The sunburst dial is sharp and even, and the stripes complement the brushed finish on the case and bracelet really nicely. Those raised hour markers, which look square at first but are actually slightly tapered at the top, add a lovely extra dimension.
The sword hands have crisp, sharp finishing, and seeing how close the hour hand sits to the dial surface really shows you just how precise the tolerances need to be.
Even the UNDONE wordmark is printed beautifully. Thick, glossy, with real visible depth. It stands out confidently from across a room.
Crystal
Yes, the crystal gets its own section. Here’s why.
This watch uses a Lexan crystal, which is essentially a very advanced, highly shatter-resistant form of plastic. Think vintage watch plastic, but engineered to a much higher standard.
I can already hear some of you sharpening your pitchforks. But hear me out.
At this level of thinness, a sapphire crystal would be both prohibitively expensive and extremely fragile. According to UNDONE’s head of PR, this is precisely why they went with Lexan. It’s a smart trade-off: yes, it’s slightly less scratch-resistant than sapphire, but scratches buff out easily with Polywatch, it’s virtually shatterproof, and it reduces reflections significantly. Looking at the dial feels almost like there’s no crystal there at all.
After a few weeks of wearing it, I haven’t seen a single scratch. Jacket sleeves, t-shirt wipes, the usual daily abuse. Nothing.
Bracelet and Clasp
The bracelet is every bit as slim as the watch itself, which is crucial on a piece like this. The top finishing is clean and matches the case quality well. It has just a little flexibility to it, which is normal at this price, and it wears beautifully thanks to rounded edges on the underside.
The pin-style links were a deliberate choice. According to Thomas, UNDONE’s head of PR, pin systems actually work better for very thin bracelets. Fair enough, and given the price, I’m not expecting custom-engineered deployant solutions.
What is exceptional here is the butterfly clasp. It’s solid, has a wonderfully satisfying click when you close it, and I genuinely could not get it to open accidentally with one wrist no matter what I tried. That might sound like a low bar, but I have watches costing 800 to 900 euros with butterfly clasps that pop open when I pull my shirt down. This one holds firm every single time.
Movement
The UNDONE Slim runs on the Ronda Caliber 1062, a Swiss-made ultra-thin quartz movement measuring just 1.9mm in height. That’s what allows the watch to achieve its remarkable 4.9mm case profile. It’s a simple two-hand movement with reliable quartz accuracy and a six-year battery life.
Honestly, this was almost the only real option for a watch like this. Ultra-thin mass-produced mechanical calibers thin enough for this case barely exist, and developing a custom in-house movement from scratch would cost millions for a very small market. The Ronda 1062 is proven, repairable, extremely thin, and purpose-built for exactly this kind of application. It’s the right tool for the job.
Comfort
At 37mm, the Slim sits in a great sweet spot. Not too small, not too big. Just right for a wide range of wrist sizes, and worth noting that a larger case at this thinness would actually be more fragile.
Wearing it is a genuine pleasure. The weight distribution is excellent because there’s so little mass on top, and the underside of the bracelet is smooth and rounded throughout. No sharp edges digging in.
One tip: because the case is slightly wider than the bracelet, I’d recommend wearing this one with a little room to move, not strapped down tight. A bit of airflow suits it perfectly and actually looks better too.
Price
At 400 euros, I think this is genuinely well-priced. Yes, it’s a quartz watch. But you’re paying for the engineering, the thinness, the custom tolerances, and a level of finishing that fashion watch brands like Hugo Boss charge 300 to 400 euros for while using cheaper Chinese movements and less thoughtful design.
The value here is real.
Conclusion
UNDONE is a brand I already liked, and the Slim is exactly the kind of move that keeps things interesting. It’s a fresh direction, genuinely well-executed, and one of the first quartz watches in a long time that I’m actually excited to reach for in the morning.
Good attention to detail, minimalist dial, excellent comfort, a unique wearing experience, and a price that makes sense. If you’re looking for something slim, elegant, and a little different without breaking the bank, the UNDONE Slim is well worth your time.
