As general matter, a business may put in place dress and appearance codes at any time and typically the law does not protect body art. That is unless such a policy violates the terms of a union agreement/employment contract or if it results in some form of legally actionable discrimination (i.e. is based on based on race, gender, age, disability and religion, etc.). Accordingly, if for example, your nose ring has religous significance, then your employer cannot bar it (however merely calling something "religious" does not automatically give it protection; you would have to give proof that it is required by your faith). Bottom line, as an "at will" worker you'll have to remove your nose ring or risk termination.