Petra Diamonds
The Cullinan mine continues to produce large stones. The Cullinan Heritage, a white diamond, was discovered in September 2009. This stone was the 19th biggest uncut diamond ever found and was sold in February 2010 to Chow Tai Fook Jewellery for $35.5m, the highest price ever paid for an uncut diamond. The previous record was held by Gem Diamonds' Leseli La Letšeng, which was bought for $18.4m by Graff Diamonds in December 2008.
Diamond enhancement
It should be noted that some irradiated diamonds are completely natural. One famous example is the Dresden Green Diamond. In these natural stones the color is imparted by "radiation burns" in the form of small patches, usually only skin deep, as is the case in radium-treated diamonds. Naturally irradiated diamonds also possess the GR1 line. The largest known irradiated diamond is the Deepdene.