Over a period of time silver jewelry starts to show changes in color and turns from a yellowish tint to deep yellow and even black. This is called the tarnishing of silver and is a natural process. The notion that silver tarnish only occurs with silver jewelry made from low purity silver is not correct.
Here, you can see the natural sterling silver tarnish before being cleaned:
To learn how to clean your CTR Ring in less than 2 minutes, watch this short video: