As a natural material, silver reacts with its environment, especially the chemicals in the air and after a while, silver does become tarnished. This doesn’t mean that your beautiful piece isn’t good quality silver.
When tarnish starts to turn any colour from yellowy brown to black you may have to get it professionally cleaned.
There are some other steps you can take, Cleaning your silver regularly is one way to avoid tarnish. But you can also avoid it by wearing your jewellery often. The oils in your skin keep it shining just be careful that when you’re wearing your silver that you don’t expose it to household chemicals, hair products, perfumes, cosmetics, perspiration, rubber, latex, chlorinated water or direct sunlight if you can help it!
To clean untarnished silver (and keep it that way), use a phosphate-free detergent or non-abrasive cloth made for cleaning jewellery.