Colmi review – the affordable smart ring is impressive

The smart rings from RingConn, Ultrahuman, Oura and Samsung cost between 300 and 400 francs or euros. That’s quite a bit of money for a bit of technology on your finger. But there’s a cheaper alternative. Colmi’s RO2 smart ring costs just under 40 francs or euros, depending on the version. I ordered one to test but to be honest I was quite sceptical.

Cheap charging concept, limited size selection

When I was taking it out of the packaging, my initial doubts were confirmed. The ring came in a small cardboard box. The packaging is simple and doesn’t look particularly high-quality. I don’t get a nice charging station or even a case. Just the ring, the instructions and a cable.

I was first disappointed with the charging set-up. You have to connect the cable to a small charging point inside the ring. It’s magnetic but it’s not exactly elegant. When power’s supplied, you’ll see a red light. When the LED lights up green, the ring’s fully charged. The small charging stations from competitors or the charging cases with rechargeable batteries are much more sophisticated.

Now to try it on. I’m lucky that the size 12 I ordered fits well on my middle finger, where I wanted to wear the ring. Colmi doesn’t offer a sizing kit to determine the right size. The selection is also limited. Currently in our range, we only have sizes 8, 10 and 12 in gold and 8, 10 and 11 in black. In other countries, the selection is somewhat larger, but you won’t find nine sizes like Ultrahuman or RingConn anywhere. Above all, if you have thin fingers or want to wear the ring on your ring finger or even your little finger, you don’t stand a chance with the smallest size (8), i.e. a diameter of around 18.5 millimetres.

Shiny gold but not high quality

What’s the Colmi ring made out of? The manufacturer doesn’t seem to be entirely sure either. It could be stainless steel or even titanium steel – I found both on the website and in the official store. It looks like plastic to me with a shiny coating. Like cheap costume jewellery. The competition is much higher quality.

Nevertheless, the Colmi ring hasn’t been scratched even after two weeks of everyday use. The material appears to be sturdy and durable. It’s definitely water-resistant. I’ve washed my hands and showered with the ring on and had no problems.

Unexpectedly good battery life with a surprising end

The next thing I noticed in my test came as a pleasant surprise. The battery just kept on going. With a total battery life of one week, Colmi can keep up with the competition. Impressive stuff. It takes 80 minutes to charge the smart tracker from 20 to 100 per cent. That’s a good charging speed.

However, I was quite surprised when the ring suddenly had no charge. I didn’t get a notification. This is because there’s hardly any communication between the app and the ring – more on this later. So it’s worth checking the battery yourself after four or five days.

Slow connection and data protection issues

To synchronise the R02 Smart Ring with your device, it uses the QRing app, which is available on Android devices as well as iPhones. You have to create an account and your data’s also stored in a cloud. However, it’s not even clear in the privacy policy, as of December 2020, where exactly this is and with which company.

The app itself was published by Shenzhen Qingcheng Wireless Technology Co., Ltd., so the data’s likely to end up in China. You have to decide for yourself whether you’re ok with that.

During synchronisation, I noticed how the ring saves power. It only connects to the app when I open it. And then it takes what feels like an eternity for the devices to connect and for all the data to be transferred. I timed it once and it was 15 seconds.

This also means that I only get a battery warning if I go into the app when the battery’s low. Otherwise, I don’t get any notifications. Depending on your own needs, this can also be an advantage. Personally, I definitely like it when a tracking app reports a step count, for example.

The app’s ok but only offers the basics

The app itself isn’t particularly exciting visually, but it’s clearly laid out. Here you’ll find all the values that the app tracks: steps taken and calories burned, sleep, heart rate, training sessions, blood oxygen and heart rate variability (HRV).

Unfortunately, in some areas, the app isn’t user friendly. Sure, I can read off all the data, but I also have to interpret everything myself. There’s no suggestions as to how I could improve my sleep. No motivation to move more. No recommended values for a general level of well-being.

It’s also a shame the data can’t be shared with other apps such as Google Fit.

Data is amazingly accurate, but not in all areas

I also have doubts as to whether the ring tracks correctly at all. So I’ve compared the data from Colmi and my Google Pixel 3 smartwatch several times and can immediately give the all-clear. The Ring seems to record data in a similar range.

One day of movement, for example, looked like this: the ring measured 11,974 steps and 7.67 kilometres, the smartwatch 11;463 steps and 7.75 kilometres. There’s a clear difference in calories. The watch calculates the daily calorie consumption. When we rest, we also have a basal metabolic rate. The Colmi ring, on the other hand, only shows the additional calories burned through exercise.

The display of the low-cost ring is somewhat confusing, because the large number displayed at the top is for a specific point in the day (in this case 545). Whereas the total for the day is further down in small print. Strange.

I also didn’t notice any significant deviations between the two devices in other random tests or when comparing the pulse rate or the blood oxygen value over the course of a day. So both should be perfectly fine for everyday use.

One thing I’m less happy about is sleep tracking. Although the ring recognises when I go to bed and get up again just like the watch, there are major differences between them. What bothers me the most is how it’s tracked. Colmi shows the total time in bed as sleep duration, in this case 7 hours and 52 minutes, while Google shows the effective sleep duration minus the waking time, i.e. 7 hours and 10 minutes.

The smartwatch tracking also seems much more accurate. While Colmi only recognised one and a half REM sleep phases, Google recognised five phases. The values are also different for light and deep sleep.

What makes me less confident about the Colmi ring sleep tracking is the evaluation in the app. Google gives a realistic value of 82 out of 100 points. The sleep was good. However for Colmi the app reveals less REM and yet 99 per cent sleep efficiency and an «excellent» sleep.