Our rosaries contain silver-plated parts and may require occasional cleaning/polishing. Please be careful when cleaning items made with gemstones and always refer to the instructions of your cleaning product. My advice to protect against tarnishing, is to store your rosary in a small ziploc bag, then store the ziploc bag inside the pouch.
The video below demonstrates a way to clean glass rosaries without the use of harsh chemicals.  Proceed at your own risk.