The Bulgari Laguna Blue is the largest diamond ever set in a Bulgari piece and is considered the most valuable gemstone ever sold by the iconic jewellery house. | Source: Bulgari Laguna Blu diamond necklace

Olivier Wagner, Sotheby's

Light of Peace Diamond, the pear brilliant-cut D-colour internally flawless beauty will appear on 7 June without a reserve price. | Source: Christie's