A 163.41-carat, D colour, flawless diamond dangles tantalisingly from a necklace at auction house Christie's in Hong Kong. The IIA-type white diamond is being presented by Swiss luxury jeweller de Grisogono ahead of the auction season in Geneva. "The largest stone that ever came up on the market before of this quality was 110 carats," said Mr Francois Curiel, Christie's chairman for Europe and Asia. "So this is a stone that is 50 per cent bigger than the previous one. It's an absolute rarity," he said yesterday. Discovered in eastern Angola last year, the 404.20-carat rough diamond was the largest ever found in the southern African country. The emerald-cut diamond, which can be detached from its white gold, diamond and emerald necklace, will also be shown in London, Dubai and New York before going under the hammer on Nov 14.