A decorative Iron Age coin dating back to 40-20BC was declared as treasure at an inquest in Wells on Tuesday.
Torquay treasure hunter David Gorman uncovered the gold coin, set in an iron mount, in March last year.
It discovered on land owned by W D Burrough and Son Ltd at Wambrook in the Blackdown Hills.
In the west of the parish at Wortheal there are substantial earthworks which may date from the iron age.
The coin was examined by the British Museum and was found to date from 40BC, and is known as a British Qb.
It was officially declared treasure by East Somerset Coroner Tony Williams.
When treasure is found – and officially declared at an inquest – museums have first refusal on ownership.
If they are not interested then the treasure can be sold, but the landowner has rights over some of the funds.