(IDEX Online) - A 21.38 carat Fancy Vivid Yellow diamond is to be auctioned tomorrow (31 January) at Sotheby's Hong Kong with an estimate of HKD 8,000,000 to 11,000,000 HKD ($1m to $1.4m).The radiant-cut VS1 gem is flanked by two tapered baguette diamonds, mounted in platinum and 18 karat yellow gold, inscribed HW (Harry Winston).The FCRF (Fancy Color Research Foundation) gives the stone a visual score of 7 out of 12. It says the stone looks slightly larger in relation to its weight, which is an important feature to consider when buying color diamonds."A large vivid yellow radiant cut diamond features a low inner grade and prominent colorless patches around the crown area," it reports. "No significant green or brown undertone is visible in the hue."The stone leads the live Important Jewels auction, Sotheby's first jewelry auction of the year in Hong Kong, comprising a selection of diamonds, colored stones, jadeites and signed jewels.Pic courtesy Sotheby's