There are several ways to distinguish real gold from fake gold, also called fool's gold, such as the presence or absence of shine, external color and weight. Genuine gold typically retains its shine in shade and in light; this is usually the quickest way to determine whether a stone is one of true gold or is made of pyrite, which is the element that creates fool's gold.
In addition to retaining shine, true gold has a brighter yellow coat and a richer, darker luster. Gold and pyrite coexist in some locations. However, some regions have historically contained one element, but not the other, which facilitates the task of proper identification.