MILAN — When even Giorgio Armani — the champion of neutrals — decides it’s time to add more color to a woman’s life, as he did in his Emporio collection, you know the tide is turning. And retailers, who have been craving more color, couldn’t be happier. Milan’s designers served up a tempting spectrum: icy pastels at Versace, Dolce & Gabbana and Anna Molinari; vivid brights at Gucci and Ferragamo, and red — the big color of choice — at both Emporio and Prada.