Gold coins

To keep things simple I use a base ten system, 10 small coins equal one large. A small coin is about the size of a dime, easily carried and stored. Nuggets and various coins from other places are all measured against that system. Gold was originally valued by the humans because of its value on earth but after the embargo, it was valued with the smugglers and the humans continued to use it for trade among themselves.

The dragons also use gold, but more for the memory factors than for an intrinsic value. Their trade has always been Goods for Goods, food or labor. You’ll see the differences begin to emerge in The HeartSinger and later in the series.