In one campaign, we play students at magical university, somewhat in the style of Harry Potter. Graduates of each college get a (non-magical) signet ring that identifies them as licensed wizards and gives them access to the restricted libraries at the schools. Our characters recently graduated, but due to an emergency, could not attend the graduation ceremony and receive their rings. It took a couple of sessions after that, but we finally got ours. Considering all the things that happened in the campaign leading up to the graduation (which took about a year in real time), those rings are more precious than any magic item.