Tarnish
The dark film that forms on silver as it reacts with sulphur in the air. Surface only, and it polishes off.
Tarnish is silver sulphide. It is a chemical reaction with the air, not corrosion, and it removes nothing from the metal.
Humidity, perspiration, rubber bands, wool and some foods all accelerate it, which is why storage matters more than cleaning.
It is not rust. Silver does not rust, and a tarnished piece is undamaged underneath.
When you are buying
Store silver in a sealed bag with an anti-tarnish strip, and never use a silver dip on a piece that has pearls in it. The dip strips nacre as readily as it strips tarnish.
925 Sterling Silver
An alloy of 92.5% silver with 7.5% other metals, usually copper. The international standard for silver jewellery.
Oxidised Silver
Silver deliberately darkened to bring out detail. In Indian markets the term is also used loosely for base-metal tribal jewellery.
Pearl Care
Pearls are soft and porous. They need to go on last, come off first, and be stored apart from everything else.
Rhodium Plating
A thin layer of rhodium over silver or white gold, giving a bright white finish that resists tarnish.