Fashion figure Loulou de la Falaise—known for her effortlessly chic style as muse, collaborator, and friend of Yves Saint Laurent—passed away in France on Saturday at the age of 63. De la Falaise designed for YSL for three decades before launching her own line of clothes and accessories. “This was someone who had an eye of her own,” InStyle fashion director Hal Rubenstein says. “When looking at Loulou, you get a true understanding of what style is all about. It’s not that she just wore Saint Laurent. It’s that when she wore his clothes and ideas, they had another life. It never looked belabored, it never looked overt. It was always consistently her. She was a true muse—she was the realization of a designer’s imagination and creativity.” De la Falaise is survived by her husband and daughter.