The Sunday Times Rich List , released once a year, always highlights the wealthiest people across the UK and lets us know exactly who in Wales has the most money. However, there’s one man born in Wales who never appears on these money lists but who has, off his own back, built a billion-dollar mining empire thousands of miles away. And what’s more, you’ve probably never heard of him. Gren (Grenville) Thomas, now in his 80s, was born in Clase, Swansea , in 1941 when German bombers were streaking through the skies. As he grew older, he loved calling into his great-grandmother’s busy pub, The Red Lion Hotel in Morriston, but crucially devoted a lot of his time to studying geology. He won a place at Cardiff University and in 1964 graduated with a degree in mining engineering. For the latest Swansea news, sign up to our newsletter here . After graduating, Thomas made the move to Canada to seek his fortune, and boy did that decision pay off. After an apprenticeship at tough nickel mines in Falconbridge, Sudbury, Ontario and then at the Giant Mines in Yellowknife in Canada’s North West Territories, he decided to strike out on his own and founded the Toronto-based Aber Diamond Corporation (named after Abertawe). In the mid-1990s, the company struck it rich by discovering the huge Diavik diamond mine, which helped Canada become one the world’s biggest diamond producers. Gren’s daughter Eira (Welsh for snow) followed in her pioneering father’s footsteps across the snowy tundra of Canada’s North West Territories. Dubbed “the Queen of Diamonds”, she helped her father discover the Diavik mine, making her the only woman in the world who can wear diamonds from a mine she discovered herself. Thomas has been a major sponsor of the Canada rugby team, and has been inducted into Canada’s Mining Hall of Fame. Speaking to Palisades Gold Radio in 2016, Thomas said: “I grew up in south Wales into a heavy industrial area. "Early on in school I started to read books, adventure stories, and one of them concerned a pilot and some prospectors in South America, so I always had in the back of my mind the idea that at sometime I would leave this rather industrialised area and head out to further parts of the world. “Ever since I started work underground - I was 16 - I always enjoyed mining, despite people saying that it must have been grim. It was actually pretty interesting to me as a young person. "And that’s why I made my entrance into mining, and then I finally left there and went to Canada and got into the mining business there and subsequently into the prospecting business.” Thomas now lives in Canada’s ‘millionaire’s retreat’ of West Vancouver, and occasionally pops into the Red Lion pub he had built - an exact replica of the Red Lion in Morriston. Despite his success, the diamond hunter has never forgotten his roots and still has Welsh newspapers such as the Western Mail sent over to Canada for him by his family in Wales. In another interview Thomas gave in 2018, he said: “I believe much of my success is attributable to my early life experiences and education in Wales and in the Swansea Valley area in particular. I’ve lived in Canada nearly 50 years but have visited Swansea at least once a year and hope to continue doing so.”