Being a fairly "international" settlement, currencies accepted are: gold, silver, copper and bronze.
Values are weighed with deben (weighing about 91 grams) and qedet (one 10th of a deben, so roughly 9.1 grams).
All coins are assumed to be 10 grams (for simplicity's sake). Silver is much more valuable than gold in the Sahara. Copper and bronze are not nearly as valuable.
Current value comparisons for silver & gold, bronze & copper & gold in KQ
1 Silver ~= 6 Gold & 3 Copper
88 Copper ~= 1 Gold
52 Bronze ~= 1 Gold
Bartering with merchandise is also accepted, and encouraged, as Qalasian economy primarily revolves around this.
Though silver, copper & bronze have their estimated gold value listed here, they don't represent the sale of these materials for gold, and direct exchanges between different kinds of coins are subject to regulation and royal approval either by the King or the Vizier, or alternatively other appointed reviewers.
EDIT: Also stickied for the time being, until we can move it someplace more appropriate.