(IDEX Online) - The world's biggest rough ruby - weighing 8,400 carats - could sell for up to $120m.The 2.8kg stone, known as the Burj Alhamal, was recovered in the village of Winza, central Tanzania, where rubies were first discovered in 2007.It is owned by the mineral and metal asset management company SJ Gold & Diamond and went on display on Friday in Dubai at the Waldorf Astoria Dubai International Financial Centre.The variegated purplish-red rough ruby (pictured) will be auctioned shortly, though no date had yet been given.Patrick Pilati, managing director of SJ Gold and Diamond, said: "This is the first time we are introducing our crown jewel of the collection."Unveiling this one-of-a-kind stone to the public for bidding, is a clear continuation of our dedication to showcasing the best of the best in the UAE."Screengrab courtesy The National