The Northern Continent: Civilizations - Draelish Clans = Clan Currency

Although the tablet features many detailed diagrams and descriptions of various gems and the methods used to cut them, the paragraph near the bottom of the front side offers a useful summary of Dirj being used as currency when dealing with various merchants of different species, as well as a snippet of a warning found a few lines further down.
...may be surprised to find that some Heart merchants are willing to trade dirj, especially when they themselves are traveling out among the border regions. However, while a Draelish will show great reluctance trading dirj to a Heart, if a Heart seeks to trade dirj to a Draelish, they will find much more value in the transaction. Thus, when needed, trade between Hearts can be done, but trade with other Draelish clans and even the Wild Kingdoms should always be preferred, as the Wild Kingdoms, though grudgingly, do still trade with the clans despite their known aloofness with the species. Better still if one can match the color of the dirj with the right Affinity, for...
...make sure to keep the crystal embedded within its metal plate when trading with Draelish, for they become greatly offended if the jewel is pried from its burial mooring...