The Vatican says Pope Francis selected a gold-plated ring believed to have once belonged to Pope Paul VI's secretary as he prepared to be officially installed Tuesday.

His coat of arms will be the same one he used as archbishop of Buenos Aires, but with a bishop's miter and gold and silver keys – both papal symbols – added.

Tuesday's ceremony, at 4:30 a.m. EST, was expected to include more than 130 government delegations, and representatives from the Jewish, Muslim, Buddhist, Sikh, and Jain faiths.

The simplified mass was expected to last for two hours.

On Monday, the pope held a private audience with the president of his native Argentina, Cristina Fernandez.

The two had disagreed over Fernandez's implementation of policies such as mandatory sex education and free contraception.