The "rules" the Amish live by are determined by the Elders of that group. They can be quite strict or fairly loose. And can vary by a fair bit from colony to colony even as neighbors. Cell phones can be fine for one group and be forbidden for the next.
Like some much in life, the rules are open to interpretation.
As a father who raised 4 daughters, you try and stop a young woman from wearing jewelry, perfumes, and even makeup. That's a fight you WILL lose every time.
You should see the dating scene. A young Amish boy holding hands with a young Native walking down a hallway, (or vice versa). It ain't right I tell you.