The colors indicate the quality level the item has. Brews, materials, medals, equipment, commands and chests containing these items all have quality levels. The level of all except materials depends on which quality gem was used to craft said item. The materials' quality level can be raised at the Forge, where you can refine and combine them. Four materials of the same quality can be used to create one gem of the next best level. There are five quality levels: white, green, blue, purple and orange, whereby white is the lowest and orange the highest level. The levels are indicated either by a colored background or with an adjective in the name or description: common, passable, valuable, epic, legendary (same order as colors).