Pure gold, such as 24 karat gold, cannot tarnish since it does not combine easily with oxygen. It is extremely rare to find a pure gold ring because base metals are alloyed alongside the gold to create a stronger and harder ring. The base metals used are exposed to oxygen and sulfur and eventually lead to tarnishing of gold rings.
14 karat gold rings or greater will see very little tarnishing if any at all. Gold rings that are below 14 karat will have less pure gold and will most likely be tarnished over a period of time. The higher the karat of gold means the less base metals used and the less likely to tarnish.
No, A tarnished gold ring does not mean it is fake, it simply means that you do not own a pure 24 karat gold ring. It is actually extremely rare to find any kind of jewelry piece made of pure 24 karat gold because it is very soft.
To remove the tarnishing found on the surface of your gold ring or gold jewelry, use a small amount of dish washing liquid that does not contain phosphate and warm water. Gently wipe away the tarnish with cotton swabs or your fingers. Toothpaste and baking soda is very abrasive and will most likely dull and scratch your gold ring. Always use 100% cotton to dry your gold rings or you can air dry your gold rings.