Judges, after all, are human. They might want to judge a project solely on its merits, regardless of how arrogant or sullen the participant may show themselves. You may have more questions to answer before the judges are convinced that you actually did all of the work yourself. This is not a good time to make an outlandish fashion statement. The BEST way to present yourself for judging is to appear to be neat.
People are people, and all things being equal, nothing is .
Judges, being human, come with their own preconceived attitudes and prejudices. You can't get around it, different people have different standards, so, for the time being, do whatever will make you look your best to the judges . This is akin to a job interview. To be honest, it is best for you to not wear any jewelry, or anything else that might be distracting. If the judges are distracted by your appearance, they will not have their full attention on your project.