Pure silver (99.9% silver) does not typically turn green. However, silver jewelry and items are often made with alloys, including copper, to increase their strength and durability. The most common type of silver used for jewelry is sterling silver, which is 92.5% silver and 7.5% other metals, usually copper. This is why you often see the hallmark "925" on silver jewelry.

The copper content in sterling silver can react with moisture, air, and substances on the skin to form a greenish or bluish-green compound called copper oxide. This can create a greenish tarnish on the surface of the silver, which is a natural and common occurrence. This tarnish can make your silver jewelry or items appear green.

To prevent or remove tarnish from silver, you can use various cleaning methods, such as polishing with a silver cloth or using commercial silver cleaners. Regular cleaning and proper storage can help keep your silver items looking their best and prevent the development of green tarnish.