In East Anglian metal-detecting terms, it is the equivalent of finding Venus de Milo's missing arms.
A lost piece of an elaborate gold torc necklace that may have belonged to Boudicca has been unearthed on Norfolk farmland by an amateur archaeologist.
The two-inch gold and silver terminal ring was lost after the rest of the torc was discovered in 1965 by a farm worker in fields near the village of Sedgeford.
That torc, valued at £3,000 at the time, was put on display in the British Museum, where it is one of the most prized exhibits in the Iron Age Collection.
The lost piece was discovered less than half a mile from the site of the original find by Steve Hammond, a retired chemist, who was surveying fields on the Sedgeford Hall Estate with a team from the Sedgeford Historical and Archaeological Research Project. Mr Hammond, 65, said it was the "most fantastic thing" he had unearthed in more than 30 years of metal-detecting.
"As soon as I cleaned some of the mud off, I realised it was the end of a torc, but I did not know the other half was in the British Museum. I did not realise how significant it was until I showed it to the site manager, who was gobsmacked," he said.
"I have found a George II gold sovereign before but nothing as exciting as this.
"I would like to find King John's jewels but I guess it is all downhill from now on."
Chris Mackie, the Sedgeford archaeology project's co-director, said: "We never in our wildest dreams thought that we would really come across the thing," he said.
The area around Sedgeford became well known for its Iron Age relics after the first discoveries in nearby Snettisham in 1948. Since then hoards of treasure containing 180 similar torcs and nearly 300 rings, bracelets and coins have been discovered.
Norfolk was the heartland of Boudicca's Iceni tribe. Some archaeologists believe she may have been the original owner of the jewellery found in Snettisham, and the broken torc discovered in Sedgeford.
Mr Mackie said that the warrior queen may have hidden her treasure in the area between sacking Roman settlements in London, St Albans and Colchester before her final defeat in AD61, thought to have been at Mancetter, near Nuneaton.
Any reward will go to Professor Bernard Campbell and his wife, Susan, who own the estate.
Jeremy Hill, the curator of the Iron Age Collection at the British Museum, said that Boudicca was known to have worn such torcs, but new research had shown that most torcs found in Norfolk were buried about 200 years before her lifetime.