I ordered a Charles Coronation Britannia. It looked beautiful when it arrived. I placed the Britannia in an Air-Tite right away. However, in less than a month it developed milk spots. I also purchased 50 non-Coronation Britannias for stacking at the same time. Now, because of the possibility of milk spots on these coins I will never buy them again. I also fear that I will never be able to get any of my premium back on these coins should they get milk spots. I should have stuck with my usual approach to stacking silver where I get generic, low premium coins. Lesson learned.