A dazzling diamond and pearl tiara with a tragic history, saved from the sinking of the Lusitania, in which the owner’s two daughters died, will be one of the star objects in the first major exhibition on the classic age of the great ocean liners, which opens next week at the V&A museum in London.

The tiara was commissioned from Cartier in 1909 by the Canadian banker and shipping magnate Sir Hugh Allan, as a gift for his wife Marguerite.

In May 1915, she was a passenger on the Lusitania, one of the largest and fastest ships on the ocean, which had not been requisitioned for the war and was still in operation carrying civilians.

Lady Allan was travelling from New York to Liverpool, planning to open a hospital in England for Canadian casualties of the war, accompanied by two of her three young daughters, and two maids. When the ship was torpedoed by a German U-boat on 7 May, within sight of the Irish coast, the valet of another first-class passenger apparently offered her his lifebelt. Although she was injured, she and the maids, and the tiara which one of them had hidden in her clothing, were rescued. Both her daughters, however, were among the 1,198 casualties, and one of their bodies was never found.

Hugh and Marguerite Allan’s only son died on his first day of war service, and she outlived their surviving daughter by 15 years, dying in 1957.

The tiara was sold at a Sotheby’s auction in November 2015 for more than £500,000, almost twice the presale estimate.

The exhibition, which opens to the public on 3 February, will include posters, film, furnishings, parts of original ship fittings – including some ornate carving from the Titanic – and glamorous clothing worn by wealthy passengers on voyages.