The change in coloration makes me wonder about how unfinished (unstained and unwaxed) pipes change color. I think the general notion is that the heat and tars from the tobacco are cooking in a darker color, but this thread would suggest that the wood darkens with time perhaps entirely unrelated to being part of a smoking pipes. My oldest Savinelli pipes bought as unfinished and almost white like new 2X4's have mellowed over 35 or 40 years to a deep resonant walnut color that looks quite deep, maybe not quite a piano finish but deeper than most well stained new pipes.