We all do a little bit of cleaning every now and then. If you are planning to do some serious cleaning, with bleach or other similar products, do beware. I received a rather desperate email from my client this week who forgot to remove her ring. Hence the picture on the left! Fortunately after a bit of sanding, matting and polishing, I got to back to new. 
The moral of this story is to take your rings off while cleaning or give up cleaning!