Cold Nights make purple buds?

I have read recently that dropping the night time temp by 25+ degrees will make the buds turn purple. Not sure if this is true will all strains, but i'm growing nirvana's ICE strain and heard this is one that will change. Just looking to see if this is true. I have convinced my wife to let me look for a mini A/C unit to do this. I understand that if it works it is only changing the look of the bud. I think it looks cool. So is this a worthy investment, or is it a pipe dream to have purple ice?

it will turn it a bluish color, its not a exact temp change or need to be an exact temp. just cool. its not worth running an a/c to show a very slight blue color that wont make it look all that good or any more potent, its mostly the stems that all turn purple/blue.