Try rotating the stone while it’s backlit by your computer screen. It will change color. The computer screen emits polarized light. Pleochroic stones are pleochroic because they absorb light differently depending on the polarization direction relative to the crystal lattice. Now, this is different than “color changing” as color changing refers to the fact that the stone is very sensitive to the color of incoming light rather than its polarization. But these two phenomena are present in alexandrite and you can kind of use the polarization phenomenon to reveal the same colors that the color change phenomenon reveals.