According to Wikipedia, they were dyed to hide the blemishes on the shell as a result of hand picking, but now that it is done by machine it's no longer necessary. Also, some people seem to think it might have been a marketing ploy.
to make it more attractive to the consumer
Pistachios are sometimes dyed red to cover imperfections in their shells, enhance their color for aesthetic appeal, or prevent people from confusing them with other types of nuts. Additionally, in some cultures, red-dyed pistachios are used as a way to differentiate them from plain pistachios in desserts or dishes.
There is a tradition of dying pistachios red, but if they are not dyed, they actually are pale green in color, and it is possible to buy them that way. The red color was just a marketing technique, to make pistachios stand out from other nuts.
dont know if this helps but ask a hair stylist
if your hair is naturally red.... DONT DIE IT loads of people love red hair.
hahahahaha! :D no......
The difference would be that is white and one is red you guess which is which
RED
mix red and blue dye Red dye- redberries blue dye- woad leaves
use a red dye on a yellow dye to get orange dye
an orane red dye in a normal form of dye but just different names
rose red dye and bonemeal