The unique artefact which dates from between the 1st and 3rd century AD was discovered by 21-year-old Danny Mills at a detecting rally near Sudbury, Suffolk.
Mills reported the find to local archaeologists and the landowner later donated it to the regional museum.
Conservator at Colchester and Ipswich Museums, Emma Hogarth, who restored the object said it is a rare and exquisite example of craftsmanship.
Archaeologists say the British Museum in London holds only fragments of similar finds and its closest complete double was found at the Roman city of Pompeii in southern Italy.
Suffolk is known to have been dotted with plush Roman villas and country estates in the 2nd century and experts speculate it could have been used by a rich landowner to move between his villa and its outhouses at night.
The lantern resembles a modern hurricane lamp and the naked flame would have been protected by a thin sheet of horn -- now decomposed -- that had been scraped until it was translucent.
What is particularly amazing about the lantern is that the chains it was suspended from still look and move like any modern chain and had not corroded into a metal lump, said Hogarth.
The lantern has recently featured in an episode on the BBC's current Digging for Britain series and can be seen at Ipswich Museum.
(Writing by Stefano Ambrogi; Editing by Steve Addison)