What to do to keep its quality? What to do to keep its quality?

Strong element or chemical is a big NO-NO. They are so violent that could possibly damage the jewellery. Chemicals like chlorine, ammonia, or bleach must be avoided as much as possible. If you think there is a need for you to clean your CZ gem that much, please see your jeweler as they are the ones who know the best thing to do. Never experiment with it yourself!