I got two R12 Colmi rings, and so far, 2–3 weeks later, both are working normally. I wear both, one on each hand. The larger one, size 22.4 compared to 21.6, seems to consume more battery, perhaps because I probably press the button by accident more often, turning on its screen. The 22.4 is also just a tiny bit too big for me, so its heart rate and oxygen tracking has some gaps in the measurements, with sleep being the main problem. So wearing the right size is crucial. The second one, which is the right size, measures everything normally

As far as I can see, since I am the first to review the Colmi r12, allow me to be detailed.
To begin with, I will say that because I wanted a smart device to monitor my health but did not want a smart watch (due to its bulk), I chose a smart ring. But why did I choose this particular smart ring among so many?
I wanted certain features, such as health monitoring, but also a good price. And I wanted it to have an LED touchscreen.
First, I will refer to its features.
Health Monitoring: It tracks heart rate, blood oxygen (SpO2), sleep quality (including light, deep, and REM stages), and stress levels using advanced biometric sensors.
Activity Tracking: It supports multiple sports modes (e.g., walking, running, cycling, yoga) and records real-time data such as steps, distance, calories burned, and exercise time.
Smart Control: When connected to a smartphone via Bluetooth 5.2, it offers smart control functions, such as remote activation of the phone’s camera, music playback control, and navigation through short videos or games.
Water Resistance: The Colmi r12 has a 1ATM water resistance rating, making it suitable for swimming, showering, and daily water exposure.
Battery and Charging: It provides an estimated battery life of 3 to 7 days, depending on usage, and recharges using a wireless charging station included. For me, the battery lasts about 4 days with heavy use. A full charge takes about an hour.
Compatibility: The R12 is compatible with devices running Android 5.1 or later, iOS 8.0 or later, and HarmonyOS, and uses the "QRing" app for data monitoring and analysis. Notably, the QRing app is good and detailed.
Design: Available in various colors and many sizes (7 to 13) to ensure a comfortable and secure fit. I got size 12. (Be careful when measuring the finger on which you will wear the smart ring. I went to a jeweler and had my finger measured for the smart ring and acted accordingly).
Secondly, I will refer to the price of the Colmi r12: I bought it along with shipping and cash on delivery, totaling €46. Definitely a very good price if compared to other competitors like the Samsung Galaxy Smart Ring.
Conclusion: Is it VFM? For me, yes. Because it gives me many features I need, has a very good price, has the LED touchscreen I wanted, and does not have the bulk of a smartwatch. And most importantly, its measurements are reliable, always in my opinion, because I compared them with the fitness equipment I have at home, and the Colmi r12 showed almost the same values for steps, calories, and heart rate.