|Q: I've got a cubic zirconium in a silver setting. I'd like to clean it; is there anything special I need to do?
A: Cubic zirconiums ("c-z") are easily cleaned with liquid detergent, such as dishwashing liquid, laundry soap, or the like. It is safest to use a mild cleaner without bleaching agents or ammonia with silver jewelry. The concern here is the finish on the sterling, by the way, not the c-z, which you're not likely to hurt with cleaning.
Soak the items in a warm solution of water and detergent, then rinse. A gentle brushing, like with a soft toothbrush, can be used to loosen stubborn dirt. If this doesn't quite do it, then a little ammonia added to the solution usually will help, but don't soak it for too long, as it can change some oxidized finishes on the sterling if left for long periods. If the silver is bright and polished, then don't worry about it.
Other cleaners that are useful are the typical spray houshold types, like Windex or Fantastic. Spray some on the jewelry, let it sit a few moments, then rinse it off. Often, that's all that's needed.
Avoid using anything with abrasives or bleach. Both will damage the silver. Don't use toothpaste, scouring powder, or "creamy" opaque cleaners, which often have abrasives. It's not so much which exact detergent you use, but to use it warm, even a bit hot, and to let the jewelry soak in it long enough to loosen the dirt. The little jars of jewelry cleaner sold commercially are actually something very similar to dish or laundry detergent..
In commercial shops, ultrasonics and steam cleaners are used. While most homes don't have ultrasonics, a method used commercially before these machines came out can generally be used. The jewelry is hung in a saucepan with a slowly boiling solution of TSP (or substitute), on (for example) an unfolded paperclip hooked over the edge. Don't let it sit on the bottom of the pan. A few minutes in there will usually clean just about anything.
Or, if one happens to have a cappuccino/espresso machine in the kitchen, the milk frothing steam nozzle is essentially a mini version of a steam cleaner, although I wouldn't advise buying an espresso machine just to clean jewelry. Just use something other than fingers to hold your jewelry under the steam, to avoid burns.. One caution here: be sure the stones are not loose before attempting to steam-clean them, or one can blast them right out of the jewelry and lose them. While it's possible to lose them in a jar of cleaning solution as well, at least then they aren't somewhere on the other side of the kitchen.
A few cautions, in general, on cleaning jewelry. Always, before cleaning a jewelry item, be sure that stones are not loose. Don't roughly grab them and twist, just touch them with a small probe, like a toothpick. Stroke the pick gently across the top of the stone- it shouldn't wiggle or shift. Also, before cleaning, be sure that the stones or c-z.s are actually set in the metal, and not just glued in. One must be MUCH more careful cleaning items where the stones are glued. Don't boil or steam them or brush them... Items with lots of tiny stones should perhaps be left to the professionals, since it's easy to loosen a few or lose them if one is not sure of what one is doing.
Also, please be aware that some stones are very fragile, or can be harmed by ordinary cleaning solutions. Amber, for example, should never go anywhere near ammonia or hot solutions of any kind. Turquoise, especially unstabilized material, shouldn't be cleaned with anything more than a soft damp cloth, since some detergents can discolor it. Leave cleaning such items to the pros. Peridot is another one that can be damaged by some stronger solutions, as can pearls, malachite, emeralds, jet, coral, and mother of pearl. Glass foilbacks look like c-z s, but the backs seem to be painted with a silver or gold paint (it's actually a mirror coating on the back of the "stone"). Anything they are cleaned with will tend to remove it. If you're not sure about the identity of your stone, and if it can be cleaned safely, make sure to ask a professional before attempting to clean it at home.
Hope this helps.