Rowan Brannan, from Bognor, was walking his dog with his mum Amanda in a field in Pagham two years ago when they made the discovery.
The pair took the bracelet to a local Finds Liaison Officer who confirmed the bracelet was Roman and probably dated back to the first century AD.
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The bracelet, unlike most other jewellery in the Roman period, is believed to have belonged to a man as a type of military armilla or battle honour for bravery.
The jewellery item is also believed to be rare in Roman Britain, especially as it is made of Gold.
The bracelet was purchased with the support of Arts Council England and the V and A Purchase Grant Fund to be showcased at The Novium Museum.
The item will be on display at the museum in Tower Street, Chichester, from September 10.
It will also be used for future research and to help explain more about the Roman period in Chichester and Arun.
It is believed to have belonged to a man (Image: Chichester District Council)
Councillor Adrian Moss, leader at Chichester District Council, said: “Acquiring this bracelet for The Novium Museum’s collection will offer our visitors additional insights into ancient practices.
“It will help shed light on military attitudes, including how Roman soldiers were rewarded for their bravery, gallantry and service, particularly with regards to the Roman invasion of Britain in AD43.
“This piece will widen our museum team’s understanding of Roman life locally and allows us to tell a different story from the Roman period.
“By enhancing the museum’s current collection with this important find, we can provide a more comprehensive narrative of Chichester District during Roman times within our permanent displays.
“The story of the find itself is fascinating — it really goes to show that you never know what you might discover by keeping your eyes peeled when out and about.”
Leanne Manfredi, national programmes lead of Arts Council England/V and A Purchase Grant Fund at the Victoria and Albert Museum, said: “We are delighted that this rare Roman gold ‘cuff’ bracelet has been acquired by The Novium Museum, Chichester, where it will be enjoyed by audiences for years to come.”
Entry to the Novium Museum in Chichester is free for everyone of all ages.