you can exagerrate it, if you want, with temps below 68F at night. if avoiding this stops the color-change, you know it's more environmental but can be genetics too. can exacerbate the displayed trait, if you want too. When it starts reflecting blue and red light (to create a purple color), it's absorbin less PAR. My 2 cents is to not exagerrate the effect, and if genetic enjoy the pretty colors, but this trait likely negatively impacts photosynthesis. i'm not a fan of it, but meh, small potatoes from what i can tell. (limited effect)