I think everyone has exercised their sense of humor on this because they don't have the foggiest idea what would cause such a thing. Nor do I. You're obviously hoping for a serious answer to your question, so I'll ask you a few things first:
What exactly does it say inside the ring? Are you absolutely sure it's really sterling?
Do you wear the ring? And if so has it come in contact with any unusual chemicals, cleaning agents, etc.
What did you clean it with?
Were the photos taken in different lighting? The one on the table appears to be in natural or fluorescent light, the other in incandescent. The one on your finger looks like it has the reflection of a light bulb to the left of the flash reflection.
Here's a bit of assay trivia: silver mixed with up to 50% gold will show no gold color at all if it's not alloyed with any other metals also. Around 50-55% gold will show a color like the ring on your finger under certain lighting conditions. It's what we called "green gold" in the assay lab. It's an old smugglers trick to cast jewelry in a 50-50 gold silver alloy and mark it sterling or 925 to avoid excise taxes or export/import restrictions on gold in certain countries, especially China and Southeast Asia. Also lessens the chances of robbery. Chances are that's not what you have, but it would be super cool if it turned out that way!
Marc