ROME (Reuters) - A rarely seen Neapolitan collection of sumptuous jewellery, hidden away for centuries and estimated to be more valuable than England's crown jewels, opened in Rome on Tuesday.
The "Treasure of San Gennaro", precious objects donated in tribute to the patron saint of Naples, has rarely left the southern Italian city and spent centuries locked in a vault, largely forgotten by the wider world.
The 70 pieces were transported under heavily armed guard to a central Rome museum earlier this month and will be on display until February.
Known in English as Januarius, the bishop of Naples was martyred in the 3rd century and remains popular among Catholics.
Thousands gather three times a year to see whether a vial of his coagulated blood will turn to liquid, which they believe to be a miracle bringing good fortune to the city.
Some Neapolitans attribute a 1980 earthquake that killed thousands to the failure of the dried blood to liquefy but skeptics say the liquefaction could be brought about by shaking or heat from hands holding the vial.
In the 1520s when Naples was struggling with plague, war and the eruption of Mount Vesuvius, surviving citizens pledged to build a chapel for the saint in return for his protection.
The vow was put in writing by a lawyer, and the original 1527 document is on display at the exhibition entrance in the Fondazione Roma-Museo.
The hoard includes what is thought to be one of the most precious pieces of jewellery in the world - the necklace of San Gennaro, begun in 1679 to adorn a gold and silver bust containing the skull of the saint.
Separate ornate pieces of jewellery were forged together over centuries to make the necklace, including a cross of diamonds and emeralds donated by French Emperor Napoleon and many gifts from monarchs dating from years when the Kingdom of Naples was a major power.
"This necklace tells the history of Europe," said Paolo Jorio, director of a Naples museum where the collection is normally kept.
The necklace includes a relatively humble pair of earrings, the only possession of a commoner spared in a disease epidemic in 1844 who donated the family heirloom to the saint.
Another centerpiece is a golden mitre, the ceremonial headdress of bishops, commissioned to crown the saint's bust in its annual procession and made of 3,300 diamonds and hundreds of rubies and emeralds, given in many separate donations.
(Reporting by Naomi O'Leary; editing by Barry Moody)