I have my own school with a children class and adults classes. One thing i have learnt from being a student of karate and now instructor is NOT to give press up's, sit up's etc, or any form of exercise as a punishment. They are part of the fitness which comes with karate training. At my club i as instructor and owner of it, before any student walks onto the dojo training area, i have to make sure no student is wearing any jewelery. I also explain why it should be removed. So maybe you should not have been put in that situation from your owner/instructor. Not wishing to sound so goody goody you are right, In the fact that you asked him to remove it and he still no matter what age or rank did not. That showed dis-respect for you as the class tutor and he should train in the spirit all martial arts student do week in week out.