Marilyn Birch, from Pontardawe in Neath-Port Talbot, told Sky News that it was an “emotional” reunion.
Mrs Birch, 76, lost the ring while feeding hay to cattle on the family farm in 1970.
After retracing her steps, she could not find the item of jewellery anywhere.
“I kept looking now and again just in case we’d spot it somewhere,” Mrs Birch said.
But detectorist Keith Phillips had other ideas. He had called at the farm several times recently to explore the land for its treasures.
“He used to show us various coins and bits and pieces he’d find on various parts of the farm,” Mrs Birch added.
“And one evening when he was leaving here, I said to him as a joke ‘now, listen now Keith, never mind all this rubbish you’re finding, go and find my engagement ring for me’.”
They both laughed it off at the time but a week or so later Mr Phillips called back with Mrs Birch’s engagement ring.
“[It was] buried eight inches down in one of the fields,” she said.
Mrs Birch has cleaned the soil off the ring with a toothbrush and says it has not come off her finger since.
“I was actually speechless,” Mrs Birch added.
“It felt quite emotional, and Keith was quite emotional about it as well because he was so delighted that he found this ring for me.”
Her husband Peter Birch turned 80 in January but the celebrations had to be postponed.
Now though, after the ring reunion, there’s all the more reason to celebrate.
