Purple-- grey = useful only to sell to a vendor to get credits- white = standard useful item, like a medpac- green = premium (somewhat rare) useful item, usually equipment like armor or weapon, but also material components for crafting. green versions of more common items can be crafted by repeated reverse engineering the basic version.- blue = prototype (rare) items, much less common than green. blue versions of green items can be crafted by repeated reverse engineering the green version.- purple = artifact (super rare) items, much less common than blue.- deep purple = epic level. not much is known but it is the top of the line so far.- orange = fully modable item. this is different from other games. it is an item that, theoretically, can be made usable at any level with the proper modifications. this means if you get it at level 10, and really like the way its aesthetics, you can keep it and just upgrade its mods and use it for the rest of your characters existence.in general the rarer an item, the better it will be. however, low level blues can be worse than high level greens, for example, so you cant just assume. you do have to check the stats.