Auction introduction: This week Sotheby’s unveiled one of the world’s purest, most saturated pink diamonds ahead of its standalone, single-lot auction scheduled for 5 October in Hong Kong. At 11.15 carats, the Williamson Pink Star is second-largest internally flawless, fancy vivid pink diamond to ever appear at auction. Yielded from a 32-carat rough diamond at the Williamson Mine in Tanzania, the Williamson Pink Star has since been masterfully cut into a dazzling cushion-cut, bringing out the diamond’s innermost beauty to full display.