Painstaking detective work has linked gold nuggets found in a Cornish castle to a 3,600-year-old German artefact recovered in a sting operation.

The Sky Disc of Nebra is a Bronze-age astronomical disc used to determine the seasons for sowing and harvesting in the Halle area of Saxony-Anhalt, Germany.

Beautifully embellished in blue and gold, it is believed to be the only known example of its kind and is rumoured to be insured for 1million Euros.

Now experts have discovered that gold from the Carnon Valley, Cornwall, are from the same source used to decorate the ancient Sky Disc.

It was a mineralist detective hunt spanning centuries and continents, led by Caerhays Castle mineral collection curator Courtenay V Smale, working with German Professor Gregor Borg.

The disc was first discovered by two metal detectorists on a protected archaeological site in 1999.

A sting operation carried out in Basle secured the million-euro relic for the State Museum of Prehistory in Halle, Saxony-Anhalt in 2002.

The connection came to light when Courtenay Smale, curator of the Mineral collection at Caerhays Castle, Cornwall, found a cache of gold nuggets hidden in the castle by its former owner.

In 1893 John Charles Williams, the owner of Caerhays, gave away most of the Estate's mineral collection to the Natural History Museum and others, but kept a small selection hidden throughout the castle.

In 2011 the curator discovered a cache of some 30 gold nuggets, secreted in a drawer with other family memorabilia.

The nuggets came with no information but the fact some contained traces of tin and that the Williams family mined the nearby Carnon River, indicated they came from the Carnon Valley.

In 1851 John Murray wrote in his ‘Handbook for Travellers in Devon and Cornwall’ that the Williams family owned "a valuable cabinet of minerals, including several large pieces of Cornish gold".

While researching Cornish gold the curator came across a German research project trying to trace the gold in the Sky Disc of Nebra.

Professor Gregor Borg, of the Martin-Luther University in Halle-Wittenberg, came to visit Caerhays in May 2017 and tests matched the gold in the Sky Disk to the Cornish nuggets.

An antler pick discovered in the Carnon Valley has been proven to be of the same age as the disc.

The Cornish gold nuggets were put on display in Munich alongside a replica of the Sky Disk at the Munich Mineral show in October 2018, which saw 40,000 visitors.

Speaking about the discovery, Courtenay said: “We were absolutely thrilled to make this remarkable link between the gold nuggets from the Carnon Valley in our Caerhays Mineral Collection and the Sky Disc of Nebra.

“I would like to offer my thanks to Professor Borg who made this discovery possible.

“We very much hope people will come to the Caerhays House Tour to see the nuggets for themselves and find out more about this exciting historical find.”