On Mon, 2009-04-13 at 12:16 -0700, David Peterson wrote:

> So, two questions.  First, does anyone have an at least semi-worked
> out monetary system in any of their conlangs, and would you
> care to explain it?

In the days when coins were worth their weight in precious metal, you
could get interesting complexities by using two metals. In Britain, from
the late Middle Ages to the early nineteenth century, we used both gold
and silver, and so had two parallel systems whose relationship
constantly changed with the bullion prices. The problem was solved in
the nineteenth century by making the silver semi-token: the coins had
enough silver to be taken seriously, but not so much that the value of
two silver crowns would ever be likely to overtake that of a gold

On Earth, gold is usually worth 10 to 15 times as much as silver, so two
coins of a similar size can give a useful ratio of '12 X = 1 Y'. 

The Chinese system was interesting in having only one coin, a low-value
iron token, and using strings of them for larger amounts. Seriously
large payments had to be made in silver ingots.