Investiture -- The Ring

In ancient times rulers and other important leaders wore a "Signet Ring" on thir hand - usually bearing the person's personal seal or "chop." They would press this ring into wax to seal official documents making it clear to the recipient that the document had the official approval of its originator.

In the Church each bishop wears such a ring -- usually made of Amethyst and sometimes bearing his or her Official Seal -- as an official symbol of his/her office.