(IDEX Online) - A flawless 103.49-ct diamond sold for over $20m at Christie's New York, beating its high estimate of $18m.The Light of Africa Diamond (pictured) is a D-color, Type IIa emerald-cut stone, from the iconic Cullinan mine, in South Africa.It was cut and polished in South Africa from a 299.3 carat rough stone, which was sold to Stargems DMCC, Dubai-based arm of the Antwerp diamond supplier, for $12.18m.Rahul Kadakia, international head of jewelry at Christie's, said: "The 103.49ct Light of Africa D Flawless diamond achieved an incredible $195,000 per carat demonstrating the strength of the diamond market at the highest levels."Christie's said it was the fifth most valuable colorless diamond it had ever sold, realizing $20,084,000.The Magnificent Jewels auction, on 8 June, achieved a total of $48,872,000 with 95 per cent sold by lot and 98 per cent by value.