title_body: Bialetti Moka Express Pot
upvoted_answer: This may be an anecdotal answer, but it's coming from a friend that really cares that their aluminium moka pot stays in a prime condition as long as possible:
  If you want to minimize visual changes in your moka pot, make sure to rinse it (do not use soap) right after use, wipe it with a dry cloth afterwards, and do not reassemble it until it's dry (as it will trap the remaining moisture in the chamber which causes the aluminium to oxidise, changing the colour). That should slow down the process significantly.