cleaning sterling silver?

Yahoo Hates Personalities asked:
i have a floating heart necklace from hot diamonds in sterling silver. it’s plated rhodium and is starting to scratch and not be as shiny as it was when it was new.
any ideas for cleaning/polishing it?
i already tried sterling silver jewelry cleaner and it didn’t do much.
i forgot to mention that i [...]

Did I just ruin my silver and diamond ring?

Becca asked: I put it in some liquid all-purpose jewelry cleaner, and forgot about it for an hour, and when I pulled it out, the band was black. I’ve been scrubbing it for a few minutes, and it’s lightened up, but it’s not shiny anymore. Did I ruin it?
Oh, yeah it was expensive. [...]