Later, "gold" was used to refer to money. For example, we often see "a reward of 500 Jin 1 Jin" in TV dramas, but in fact most of them refer to copper coins.
Some sources say that "gold" is what we now call "silver", which probably means that "gold" was once used as a substitute for currency, and silver is an ancient currency.
Because "gold" was the most precious metal in ancient times, "gold" once again became a special term for gold.