I agree with Camille. And now that you've cleaned it up, it looks GREAT to me. Good job trimming it up. Remember... good drainage but likes to stay hydrated.
I don't see a purple ring, just a purple spot. If that spot is on the same side as the brown patch, then it's probably just the rot which spread further down.
Here's another picture, we enhanced the colours a bit but you can see it a lot better now. The purple is present throughout the plant as far as I can tell, even on the newest growth.