Romancing the stone: Louis Vuitton shows off huge rough diamond The biggest rough diamond discovered in over a century was shown to private clients Tuesday by French luxury handbag-maker Louis Vuitton, which acquired the 1,758-carat gem to make a big splash in the high-end jewellery market. The stone named "Sewelo," meaning "rare find" in the tswana tongue of Botswana where it was discovered, is the size of a tennis ball.