VATICAN CITY—One of the gems of the Vatican’s priceless religious art collection—a 6th-century reliquary containing what are revered as fragments of the cross on which Jesus was crucified—has been restored to its Byzantine-era glory.

The Vatican unveiled the restored Crux Vaticana, a foot-high jewel-encrusted golden cross containing what tradition holds are shards of Jesus’ cross inside.

Byzantine art experts said the restoration rendered the cross much closer to what it would have looked like at the time the Byzantine Emperor Justin II gave it to the people of Rome.

The cross will be on public display inside St. Peter’s Basilica through April 12.