ple·och·ro·ism 
(plē-ŏkrō-ĭz′əm)
(plē-ŏkrō-ĭz′əm)n.
The property possessed by some crystals of exhibiting different colors, especially three different colors, when viewed along different axes.
[PLEO- + Greek khrōs, color + -ISM.]
ple′o·chroic (plē′ə-krōĭk) adj.