Pure silver is less prone to oxidation and blackening than impure silver. Silver with low purity is particularly prone to blackening, and silver will be oxidized to blacken when it meets sulfur and sulfur oxides.
But if it turns black, don't worry. There are many ways to clean silver after it turns black.
1. Wipe silver cloth, which is sold in some shops selling silver jewelry.
2. Detergent, the kind that washes dishes at home, is better with warm water.
3. Toothpaste, if cleaned with toothpaste, because it contains abrasives, if it is particularly bright, the surface of silverware will leave tiny scratches.
Baking soda can also be used to clean silverware.
If you don't wear it for a long time, remember to wrap it in a soft cloth, clean it and put it in a sealed bag for long-term storage.
References:
How to clean a silver necklace