An "exceptionally rare" diamond necklace from the 18th century is displayed at Sotheby's in London ahead of going under the hammer in Geneva in November, where it is estimated to fetch between $1.8 and $2.8 million. It is thought that some of the diamonds may have come from the famous necklace linked to what became the scandal of the "Affair of the Necklace", which contributed to the advent of the French Revolution and eventually Marie-Antoinette's death. Sotheby's cannot confirm this link, but the chairman of the jewellery department, Andres White Correal, hails the necklace as "highly important". IMAGES AND SOUNDBITES