Color Change refers to the outcome of ‘fuming’ (adding a very thin layer of precious metal) before final annealing and depositing leaf resin on the inside of the pipe (through use). Light is reflected from the shiny interior resin layer, through the atomic deep layer of precious metal (typically silver or gold) where the fume layer acts like a prism and a filter; breaking viewable light down into it’s colored bandwidths and then cancelling all but a specific few colors, causing the glass to appear to change color. Silver leaves a slightly yellow transparent hue and changes to Blues and Greens while Gold leaves a slightly pink hue and changes to Red and Orange. Silver and Gold turns purple.