Gold coin
Gold coins or gold is the currency in all Dragon Quest games. It is used to purchase armour, weapons, items, and tokens for the Casino. It is usually won in battles, found in chests, or otherwise gained as a reward for completing missions.
The value of gold coins is not consistent across Dragon Quest titles and a particular item frequently costs more or less depending on the game. That said, it's interesting to note that gold coins can be considered a sort of auxiliary world currency, as they are accepted everywhere throughout a particular game's world (though even in that world one item may have a differing value, possibly suggesting a sort of exchange rate.)