Why are pink diamonds so popular? From multimillion-dollar sales with Sotheby’s Williamson Pink Star and Harry Winston’s gem to Graff – one of the rare jewels is even named after Grace of Monaco

• Pink diamonds have long been revered for their rarity and beauty – but when Sotheby’s sold its record-breaking Williamson Pink Star for US$57.7 million, ears pricked up
• The pretty gems are now on every maison’s radar, with top-quality ones growing exponentially in the past decade amid the closure of the Argyle diamond mine in Australia