London, Sep 27: One of London's top diamond companies announced on Tuesday it bought the world's largest rough diamonds, a rare gem the size of a tennis ball. The diamond has been sold for $53 million, according to Xinhua. Laurence Graff said following successful negotiation with the Lucara Diamond Corp, his company has acquired the world's most valuable rough diamond, the Lesedi La Rona, weighing a record-breaking 1,109 carats. Graff's company said the deal was closed with a handshake after more than a year of negotiations. The diamond was put up for auction last year, but failed to reach its reserve price. A spokesperson at Graff said: "Discovered at the Lucara Karowe mine in north-central Botswana, the hypnotic Lesedi La Rona is the largest gem quality rough diamond discovered in over 100 years." "This magnificent stone has been identified by the Gemological Institute of America as possessing exceptional quality and transparency, earning the full significance of its name, which means 'our light' in Botswana's Tswana language," he added. Laurence Graff said: "We are thrilled and honoured to become the new custodians of this incredible diamond. Our highly skilled team of master craftsmen will draw on many years of experience of crafting the most important diamonds, working night and day to ensure that we do justice to this remarkable gift from Mother Nature." The acquisition follows Graff's purchase earlier this year of a remarkable 373 carat rough diamond that was originally part of the Lesedi La Rona rough, making this poignant reunion for the two stones: both now owned by Graff.