Cleaning the jewelry...
I recommend using Sunshine or Moonshine polishing cloths or Pro Polish Pads. Do not use dips to clean your jewelry. Dips can remove oxidation (the darkening that is supposed to be there), so a soft cleaning cloth (included with each order) will wipe away the tarnish while preserving the intended oxidation.
Harsh chemicals like chlorine (and shocked swimming pools), bleach, and sulfuric water will blacken silver and ruin stones. You can always clean real silver. If your jewelry has stones in it, try as best as possible to avoid any liquid chemicals (especially in swimming pools), heavy sweating, manual labor, or dropping the piece as this can damage the stone and possibly the silver. I cannot fix broken stones.