A rare Sun-Drop Diamond has been sold for more than £6.89 million ($10.9 million) at Sotheby's auction house in Geneva. The pear-shaped yellow diamond is the largest known yellow gem stone in the world.

The diamond has been bought by a telephone bidder in an auction held on Tuesday. It was estimated to fetch £6.95 million to £9.48 million ($11 million to $15 million) by auction house Sotheby's.

The rare diamond weighing 110.03 has been graded as Fancy Vivid Yellow, the highest colour grading, by the Gemological Institute of America (GIA). It is ranked as the largest known pear‐shaped fancy vivid yellow diamond in the world, and has a purity of VVS1.

The rare Sun–Drop diamond was discovered in South Africa in 2010 and was sold by Cora International, a New York-based manufacturer of exceptional diamonds.

The previous record for the largest yellow diamond was held by a pear-shaped fancy yellow diamond 'The Vivid Yellow', weighing a32.77 carats. It was sold at Christie's New York on October 2011.

The colour in yellow diamonds is caused by nitrogen impurities trapped within carbon molecules and hardened over the course of millions of years.