Rose de France is a member of the amethyst family of gemstones. It is defined by its markedly light shade of the purple known to the amethyst family. The color is reminiscent of a lavender/lilac shade.
Amethyst is found in a variety of hues of purple including deep purple, light lilac, lavender, and mauve. The pale lilac colors, coined Rose de France, were once considered undesirable but have recently become popular due to intensive marketing.
References
Rose de france Wikipedia(Text) CC BY-SA