28-year-old Katy Perry and 25-year-old Rihanna have developed a rather close friendship over their years in the spotlight, and during a recent interview with Elle Canada, Perry commented on her friend's fresh looks despite her constant marijuana use. 

"I think Rihanna always looks so fresh and I'm like, 'How do you do that? We all know how much pot you smoke!'  And you don't sleep because you're on Instagram at four o'clock in the morning.  I love her and everytime I see her, I'm reminded of the light she has.  I know a lot of people out there with the most detrimental entourages -- they are the root of their demise. It's really unfortunate but you can't save these people. My days of celebrity saving are over."

Source: huffingtonpost.com