Store your Margherita and B piece separately all the time to protect it from knocks and scratches.
This will also keep it away from air and humidity which are the main cause of silver oxidation.
You can make your tarnished silver pieces shine again like new by cleaning it with a special cloth.
Gold plated sterling silver jewellery has a gold patina over itself, which tends to disappear naturally over time. It is not recommended to wear gold plated jewellery when you are sleeping, swimming or doing sports as this would speed up the natural process of fading. As it would be better to avoid contact with make up or perfumes.
Loss of patina is a normal phenomenon resulting from wear and tear.