Emperors of ancient Rome customarily marked anniversaries of their rule with celebrations, although they did not use the term jubilee.
Jubilee was to recognize that by tradition all property belongs to God, not the individual Jew.
[1] Following the model of Augustus, the Roman emperors typically celebrated major jubilees on the 10th years of their reigns.
The decennalia marked the 10th year, the vicennalia the 20th, and—in the case of Constantine the Great—the tricennalia the 30th.
For modern monarchs, the dates are typically connected with precious metals and gemstones: