Perhaps it's more subtle than I realized. I do see it in Moiraine, but I don't really see it in Siuan and Alanna. I wonder if they will reference agelessness in the show.
This is what I thought as well. Also, in the books, they make a big deal about how the rings marks an Aes Sedai. It has to be easily recognizable for that effect. Especially since they aren’t doing the ageless face.