The ring, which was found in a farmer’s field in 1785, is linked to a Roman curse tablet that echoes the legends created by Tolkien in his novels.
It is to go on display at National Trust property The Vyne in Hampshire where the ring — which is inscribed in Latin and inset with an image of the goddess Venus — lay forgotten for many years.
The ring, which was found in nearby Silchester, a Roman town with a famous excavation site, is inscribed with the words “Senicianus live well in God”.
In the early 19th century, a curse tablet was found at a Roman temple site in Lydney, Gloucestershire, about 128km away from The Vyne.
Written on it was a plea from a Roman, Silvianus, asking Nodens, god of the Lydney temple, to return a ring, stolen by Senicianus, and placing a curse of ill health on the thief.
Archaeologist Mortimer Wheeler, director of later excavations at Lydney, realised the connection between the ring and the curse tablet, and asked Tolkien, who was professor of Anglo-Saxon at Oxford University, to work on the etymology of Nodens.
Tolkien visited the Temple of Nodens on a number of occasions, and it is believed he would have been made aware of the existence of the ring at this time. Within a year, he began writing The Hobbit.
In addition, the area around the temple was known as Dwarf’s Hill, believed to have been an Iron Age fort some suggest was the inspiration for the dwarves in The Hobbit.
How the ring came to be at The Vyne is unknown but the owner, Chaloner Chute, included details about it in his 1888 history of the building.
The ring, probably from the fourth century, is larger than an average ring, and may have been made to wear on a thumb and over a glove.
Dr Lynn Forest-Hill, education officer for the Tolkien Society, said: “We were delighted to partner the National Trust in this project and to assist with research that may shed further light on the history of this mysterious piece of gold.”