COLMI R02 Smart Ring Review: Health Tracking Meets Elegant Design

Smart rings are having a genuine moment right now — and the COLMI R02 is one of the most compelling reasons why. At £34.02, it offers a beautiful stainless steel design, continuous health monitoring, and all-day comfort in a device that looks more like a piece of jewellery than a piece of tech. If you've ever been curious about smart rings but weren't sure whether they're worth it, this review will give you a thorough and honest picture.

The smart ring market has historically been dominated by premium brands charging £200–£400 for a device without a screen. The COLMI R02 challenges that assumption entirely, bringing the core benefits of smart ring technology within reach of almost anyone. But does cutting the price compromise the experience? Let's find out.

Unboxing and First Impressions

The R02 arrives in neat, compact packaging. Inside the box you'll find the smart ring itself, a magnetic charging cable, and a user manual. The ring is immediately striking — the stainless steel finish catches the light beautifully, and it genuinely looks like something you might pick up from a jewellery shop rather than an electronics retailer. Available in Gold and Black, both colourways have a polished, premium appearance.

Picking it up, the first thing you notice is how lightweight it is. This matters enormously for a device you're going to wear 24/7 — a heavy ring becomes uncomfortable surprisingly quickly, particularly during sleep. The R02's weight is negligible, which is exactly what you want from an always-on wearable.

Design and Build Quality

The outer shell of the R02 is stainless steel, giving it a durability and scratch resistance that cheaper alloy alternatives can't match. The inner surface, where the sensors sit, is smooth and carefully finished to avoid any sharp edges or rough spots that might cause irritation during extended wear.

Sizes available include 8, 9, 10, and 11 in Gold, and 8, 9, and 10 in Black. Getting the right size is crucial for both comfort and sensor accuracy — a ring that's too loose will slide around and give inconsistent health readings. If you're unsure of your size, we have a complete smart ring sizing guide to help you measure correctly before ordering.

The IP68 waterproof rating is a genuine selling point. You can wear the R02 in the shower, while swimming, washing up, or in the rain without any concern. The stainless steel construction also means it won't discolour or corrode with repeated water exposure — something cheaper metals often struggle with over time.

Key Specifications

Shell material: Stainless steel
Waterproof rating: IP68
Health sensors: Optical heart rate, blood oxygen (SpO2), accelerometer
Health features: Continuous heart rate, SpO2, sleep tracking, step counting
Available sizes: 8–11 (Gold), 8–10 (Black)
Connectivity: Bluetooth
Companion app: Android and iOS compatible
Price: £34.02

Health Tracking: What the R02 Monitors

The R02's health monitoring suite focuses on the metrics that matter most for everyday wellness. Here's a detailed look at each feature:

Continuous Heart Rate Monitoring

The optical sensor embedded in the inner surface of the ring continuously monitors your heart rate throughout the day and night. This is one of the key advantages of smart rings over smartwatches — because you're far more likely to wear a ring while sleeping than a watch, the overnight heart rate data tends to be more complete and consistent.

Resting heart rate data from the R02 is synced to the companion app, where you can view trends over time. A gradually rising resting heart rate over several weeks can be an early indicator of overtraining, illness, or increased stress — exactly the kind of early warning signal that makes continuous monitoring valuable.

Blood Oxygen (SpO2) Monitoring

The R02 uses red and infrared light to measure your blood oxygen saturation levels. Healthy SpO2 readings typically fall between 95–100%. The ring can take readings on demand, and monitoring SpO2 overnight can reveal subtle desaturations that might indicate sleep-disordered breathing — something many people don't realise is affecting them.

While the R02 is not a medical device and cannot diagnose conditions like sleep apnoea, consistent overnight SpO2 data can flag patterns worth discussing with a healthcare provider.

Sleep Tracking

This is where smart rings genuinely outshine smartwatches for many users. Because the ring is so lightweight and unobtrusive, most people sleep with it on naturally — which means the sleep data is continuous and uninterrupted. The R02 automatically detects when you fall asleep, monitors your sleep stages (light sleep, deep sleep, and awake periods), and generates a daily sleep score in the companion app.

Over the course of a week, you'll start to see meaningful patterns — nights when you slept deeply versus restlessly, and correlations with your activity levels, stress, or lifestyle choices. This kind of longitudinal health data is genuinely valuable for understanding your own wellbeing.

Step Counting and Daily Activity

The R02's built-in accelerometer tracks your daily step count, estimates calories burned based on your steps and body weight, and monitors your overall activity level throughout the day. It's not as detailed as a dedicated fitness watch for workout tracking, but for general daily movement monitoring, the data is accurate and useful.

Stress Monitoring

Using heart rate variability (HRV) data, the R02 provides a basic stress level indicator. HRV — the variation in time between consecutive heartbeats — is a well-established physiological marker of autonomic nervous system activity. Low HRV generally indicates higher stress or fatigue; high HRV suggests good recovery and relaxation. The app translates this into an easy-to-understand stress score.

Battery Life: How Long Does It Last?

Smart rings face an inherent engineering challenge: the ring needs to be small and comfortable, which limits the size of the battery. The R02 manages this balance well, delivering around 3–5 days of battery life with continuous monitoring active. With sleep tracking disabled and heart rate monitoring set to periodic rather than continuous, you can stretch this to 6–7 days.

Charging is handled by the included magnetic charging cable. The ring sits on the magnetic charger and charges from flat in approximately 1.5–2 hours. The magnetic connection is secure and reliable — no fumbling with tiny ports or fiddly cables.

If extended battery life is your priority, the COLMI R07 is worth considering — it offers up to 30 days of battery life on a single charge, making it the longest-lasting option in the COLMI smart ring range.

Comfort and Long-Term Wearability

Comfort is where the R02 really wins. After the first hour or two of wearing it, you'll genuinely forget it's there. There's no screen to catch on things, no strap to tighten or loosen throughout the day, and no bulk on your wrist to bump into things. The smooth stainless steel glides rather than drags, and the weight is imperceptible.

This is particularly significant for sleep tracking. Many people who try smartwatch-based sleep tracking give up because the watch is uncomfortable to sleep in — the screen can catch on bedding, the strap can feel tight or sweaty, and the haptic feedback from notifications can wake them up. None of these issues exist with the R02. You simply put it on and forget about it.

For people with desk jobs who type extensively, a ring on the right hand can occasionally feel more noticeable than on a non-dominant hand. We'd recommend wearing it on whichever hand types less — typically the left hand for right-handed users — to maximise comfort during long working days.

The Companion App

The R02 pairs with a smartphone app (compatible with both Android and iOS) that presents all your health data in a clean, accessible dashboard. The home screen shows your daily step count, heart rate, SpO2, and sleep score at a glance. Tap any metric to explore historical data in chart form — daily, weekly, and monthly views help you identify trends.

The app also allows you to set health goals, configure notification preferences, and review detailed breakdowns of each night's sleep data. The interface is straightforward and doesn't require any technical knowledge to navigate — it's designed for everyday users, not tech enthusiasts.

Smart Ring vs Smartwatch: Which Should You Choose?

The R02 is not trying to replace a smartwatch — it's doing something different. It can't show you notifications, play music, or track your outdoor run with GPS. What it does is monitor your health continuously, comfortably, and discreetly throughout every hour of the day and night.

For many people, the ideal setup is a smartwatch for daytime interactions and workout tracking, paired with a smart ring for overnight monitoring. The R02's price makes this combination very accessible — buying both the COLMI V69 and the COLMI R02 together would cost under £75, giving you comprehensive wearable coverage at a fraction of what you'd pay for a single premium device.

If you want a single device that covers everything, a smartwatch is still the more versatile choice. But if your primary focus is health monitoring — particularly sleep and resting metrics — the R02 (or another smart ring) will often give you better data quality for those specific measurements.

Comparing the R02 to Other COLMI Smart Rings

The COLMI smart ring range offers several options at different price points and with different features:

COLMI R03 (£36.03) — Adds a portable charging case for on-the-go charging. Worth the extra £2 if you travel frequently.
COLMI R06 (£39.06) — Upgraded to 5ATM waterproofing (deeper water resistance) and a longer battery life.
COLMI R07 (£42.07) — The battery life champion: up to 30 days on a single charge.
COLMI R12 (£56.12) — The premium option with a touchscreen display directly on the ring.

The R02 is the right choice if you want to try smart ring technology at the lowest price while still getting a high-quality stainless steel product. It's an excellent entry point into the category.

What We Liked

Beautiful stainless steel design that looks like real jewellery
Exceptional all-day and overnight comfort
Accurate continuous heart rate and SpO2 monitoring
Reliable sleep tracking with stage analysis
IP68 waterproof for swimming and showering
Clean, easy-to-use companion app
Excellent value at £34.02

What Could Be Better

3–5 day battery life requires more frequent charging than some rivals
No display — all data requires the smartphone app
Limited size range in Black finish (only 8–10)
No dedicated workout tracking modes

Who Is the COLMI R02 Best For?

The R02 is an ideal choice for:

People who want health tracking without the look or feel of a traditional smartwatch
Those who find smartwatches uncomfortable during sleep
Anyone looking for an elegant, jewellery-like wearable
People curious about smart ring technology who don't want to spend £300+ to find out if they like it
Users focused primarily on sleep quality, resting heart rate trends, and passive daily health monitoring

Our Verdict

The COLMI R02 is a compelling, thoughtfully designed entry into the smart ring market. It looks the part, tracks the right metrics, and offers the kind of all-day comfort that a smartwatch simply cannot match. The stainless steel construction feels premium, the health data is accurate and useful, and the companion app makes the most of the data collected.

At £34.02, the R02 is one of the most affordable ways to experience smart ring technology without compromising on build quality or health tracking accuracy. If you're ready to make health monitoring a seamless part of your daily life — without anyone even knowing you're wearing a tracker — the R02 is an excellent place to start.

👉 Buy the COLMI R02 Smart Ring — £34.02