(IDEX Online) - Christian Dior yesterday unveiled an 88.88-carat cushion-cut yellow diamond - worth an estimated $50m - at the re-opening of its flagship store in Paris.The fancy intense VVS2 stone was recovered as a 150-carat rough gem at the Kimberley mine, South Africa, owned by Ekapa.Dior acquired it for an undisclosed sum and insisted on cutting it to exactly 88.88-carats, reflecting its belief in eight as a lucky number.The jeweler's maison has eight workshops on eight floors and is located in the 8th arrondissement of the French capital.The gem has been named the Montaigne Diamond, after the address of the store - 30 Avenue Montaigne. Dior's birthplace re-opened after a two-year refurbishment.The diamond has been set in an ornate two-finger ring designed by Victoire de Castellane, artistic director of Dior Joaillerie. The piece has been valued at $50m by the Financial Times.