As for the question regarding PM bracelets, I know Rolex has been using ceramic sleeves on Platinum DayDate IIs for a while and is now using them on all DayDate 40s now.
Historically, the bracelet was composed of gold links containing steel inserts. In the new version, these steel inserts are covered by ceramic sleeves, which raises durability by reducing the wear-and-tear that results when soft and hard metals rub against each other. It may be a minor improvement but one that is proof of Rolex’s commitment to quality.
Taken from article:
https://www.forbes.com/sites/yjeanmu.../#20921c371d64