Rings can turn a finger black, or some might say green. If you have a ring of quality metal, it doesn't mean that the problem won't occur. Even precious metal like gold can turn your finger black. One of the reasons for this is the acid in your skin. The acid reacts with the gold, and this can turn the skin that comes in contact with the ring black.
Besides the acid in your skin, other things can create a reaction that will turn the skin black. Hormone changes in a woman can create an imbalance in chemical make-up that turns skin colours. This can be temporary or permanent, depending on the person and how much her hormone levels change during the menopause stage.
Environmental factors such as chemicals used or that come in contact with the skin can also affect the skin and turn it black. Chlorine is one chemical that can damage jewellery. This exposure comes from pools and jacuzzis as well as some cleaning solutions. It breaks down the gold, causing black to appear that rubs off on the skin. Make-up is another cause of chemical reactions. It can scrape at the gold, making small flecks of gold come off. The flecks are so small they can appear black. Salt air can cause a reaction as well when it mixes with sweat to create a chemical reaction.
In most cases, jewellery is not made of just precious metal. Rings are made up of an alloy of silver or gold and other metals to make them strong enough to withstand wear and tear. In some cases, you might have an allergic reaction to the alloy that causes your finger to turn colour. This is especially true with cheaper silver jewellery that has nickel in the mix. If an allergic reaction is the cause, there isn't much that can be done except to try a different ring with a different metal composite, or in some cases a coating on the ring in the form of rhodium plating. This will keep the skin from coming in contact with the metal that is causing the reaction.
The best way to fight these effects is to know when and when not to wear rings, and to take them off at night. Clean them often, and if worn when working with chemicals, clean them and your hands immediately.