Chef color coral

A friend of mine and his girlfriend came over to my house tonight and saw my xenia. His girlfriend really liked them but thought they were a little plain. I told her they were called pink pulsating xenia. She is a chef and asked could you dye the xenia outside of the tank and then place them back in the tank a new color. I told her I had no idea but would ask the experts here. I'm curious.
So has anyone ever tried using food coloring on any of their corals to make a new color or change the color of their coral?
My answer: I would think the coloring would work; HOWEVER, the dye would come out in saltwater. That's an interesting question.
Who has the answer?

 

Its a semi common practice on alot of soft corals including colt corals and kenya trees. The color fades after a few weeks but I don't know how hard it is on the coral. Alot of people think its inhumane.