When an 11-year-boy dug up a wedding ring in Norway at the weekend, he could scarcely believe the swiftness with which the mystery unraveled and the gold band was reunited with its owner 13 years after it disappeared.

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Martin Rissmann was out hunting for treasure with a group of adults and other children on Bjørkøya, a small island off the south coast of Norway, when his metal detector suddenly started beeping, newspaper Verdens Gang reports.

Digging in a patch of ground where a caravan had once stood, the delighted young forager pulled out a ring with the inscription: “Your Hans Jakob 19/7-85”.

Keen to trace its origins, Rissmann immediately showed the ring to Ida Kjellemyr, the tour guide leading the expedition.

Kjellemyr, 20, described how she gave an excited leap on reading the inscription.

“I saw that it said Hans Jakob, and that’s my dad! I knew mum had lost her wedding ring when I was small.”

She instantly contacted her mother, Bjørg Kjellemyr, 45, who recalled the day in 1999 when she and her husband took their dog for a walk with another couple on the island where they were holidaying.

The older woman remembered suffering slightly from eczema and scratching at her hand along the way. When they returned to the caravan, she realized to her despair that she’d lost her wedding ring. Although they retraced their steps with their friends, the ring was nowhere to be seen.

Bjørg Kjellemyr said she never replaced the ring but thought about it often, particularly on special occasions like her recent 25th wedding anniversary.

For a brief moment, however, her daughter wondered if she had been mistaken.

“Ida rang and said: ‘Mum, when did you get married?’

“1986, I said.”

The younger women explained that the inscription appeared to date the ring to 1985. But her mother quickly remembered that the date inscribed in the wedding ring was in fact the date on which she and her Hans Jakob had got engaged.

“’Is it possible?’ I said then, and my daughter confirmed that it was true. It just made me so wonderfully happy,” she told Verdens Gang.

Bjørg Kjellemyr said she had already arranged a reward for young Martin Rissmann. On hearing where the ring was found, she noted that she must have lost it back at the caravan when she returned from her walk on that day 13 years ago.

“It’s just incredible; I’ll have to thank Martin for a fantastic job. And it was so fortunate that my daughter was there that particular day,” she said.