Well, designed in Italy but made in China could be told also of a lot of designer items with an high price tag. Personally I would avoid big names.
A chain that can be found in several cities with classic women apparel is Luisa Spagnoli. In Florence they have two branches, both in the very center. Coin and Rinascente are two department stores with branches in several cities that usually sell high quality goods (but I would expect that most of the items are made in China anyway).
A problem with high end stores is that they seem to keep mostly small sizes. An insider suggestion from a Florentine: if you are looking for no-nonsense but high quality apparel, head to the relatively small Baccini shop, via Pisana near Porta S. Frediano. You enter and ask what you want and they will bring an endless selection, often more things that you would find in a department store. After me and my wife discovered this family owned shop, we buy most of our clothes from them.