The wide ring band tapers from 18 mm auf 8 mm.
The usual Aztec calendar follows the solar year and is called Xihuitl. It shows close resemblance to the older Maya calendar. It has 18 months with each 20 days and 5 additional days which were said to be full of misery. The last day of every week was market day and high and rest day at the same time. Further there was the holy calendar used by priest for prophecies. Each day was allocated to a god. Fate depended on whether the respective birthday was attributed to good or bad features.