Color changing pipes or fumed pipes are some of the funnest pipes out there. How these pipes change colors is that when they’re made they’re fumed with a precious metal, usually 24k gold or .999 fine silver. Then as these pipes are used the resin starts to interact with the fuming and will change colors. The more the pipe is used the more it changes colors. The cool thing is after its cleaned it will go back to how you got it when it was brand new and you can start changing the colors all over again.