The godmother will be a travel agent, chosen after a selection process and competition running between July and September.
The ship will be docked at the Ponte dei Mille and festivities will begin at 5 p.m., culminating in a gala dinner on board. Costa Diadema will sail overnight from Genoa to Savona.
The €550m Costa Diadema is under construction at the Fincantieri shipyard in Marghera and will be delivered October 30.
Following will be a month-long festival, which will include the vernissage cruise of November 1, the naming ceremony on November 7 and three inaugural cruises starting  8, 15 and 22 November.
From November 29 and for the winter season 2014/15 and summer 2015, Costa Diadema will operate weekly cruises that depart from Savona and call in Marseille, Barcelona, Palma de Mallorca, Naples and La Spezia.
Costa Cruises is expanding its presence in Genoa with the opening of new offices for about 250 employees in Piccapietra Square, next to the current headquarters. The new offices will be ready this summer.