性质 vs 性格 vs 个性 - all mean personality? Sad to say, my research has thrown up basically nothing on the differences between these three words, which is a bit annoying. They all seem to be someone's personality. Am I right in thinking that they are therefore fully interchangeable?! 

(Grrr, why does Chinese have so many similar words...?! Or - more to the point - why are dictionaries so pants at distinguishing them lol Thinking of writing my own Chinese dictionary...!)
As Becky stated 性质 = property. It is unrelated to personality


性格 = personality
个 in 个性 means individual, therefore, 个性 implies 个人性格 (individual personality)