How to Determine the Value of Gold in a Fantasy Setting

In fantasy settings it does seem less likely that units of value like paper money are going to be common. This is because they may have not come up with a way to mass produce something like paper money. The value of an aura like gold is based on its rarity as I just said and if new planets are being discovered this is going to have an impact on the value of gold back home. Another issue here is that it's not just gold that's going to be found in different quantities but all sorts of other things that can quickly get complicated and overtake our story. We have several options we want to keep in mind when it comes to currency.