DRK: The "platinum"... Platinum is a catalyst and is used in specific applications for its catalytic properties. Doesn't corrode no matter what. It's also mined at much lesser quantities than gold (scarcer) at a ratio of 150 tons (platinum) to 2500 tons (gold) to 25000 tons (silver). Mining production and scarcity of DRK adequately positions it as the platinum. (4.4mn coins vs 13mn BTCs)
Try to relate it to treasure somehow, like Gold?