[6] Costa Diadema features a total of 1,862 cabins that can accommodate a maximum of 4,947 passengers and 1,253 crew members and also has an outside promenade extending over 500 m (1,600 ft).

[6] The ship includes three swimming pools, three dining areas, a 4D cinema hall, and a Saṃsāra spa across four decks.

[10] Costa Diadema had her keel laid on 10 December 2012 at Fincantieri's shipyard in Marghera, marking the beginning of her hull assembly.

[14] Her naming ceremony was held on 7 November 2014 at the Port of Genoa, where she was officially christened by Italian travel agent, Carolina Micelli.

[16] On 24 March 2020, the ship docked at Limassol, Cyprus, and a crew member suspected of suffering from the coronavirus was taken to hospital.