You can buy a lot of expensive jewellery cleaners but we recommend you use only a soft and clean cloth (cotton or flanel) and if necessary warm soapsuds(using a mild detergent soap). It will not harm any type of material unlike the jewellery cleaners. Rince well with cold water and dry it thoroughly before storing.You can also use a very soft tooth brush to clean your stones and settings.
Instead of a normal soft cloth , you can buy special polishing cloths if your jewellery need a more intense cleaning.Never use a polishing cloth on your pearls.
The best tip we can give to avoid your jewellery from tarnishing or staining is to wear them regularly. If you are not wearing your jewellery and you have not stored them properly, they will tarnish faster.