The StarStable Database by Abbie Starwatcher provides a comprehensive inventory of clothes, horse gear, decoration items and hairstyles available in the game.
Most information and all pictures originate from the German version of this website. If you want to see them, please switch to the German version (icon on top of the menu). You can find them at "Kleidung & Accessoires", "Ausrüstung & Deko" and "Frisuren & Make Up". I won't copy them here because it was a lot of work and I think that the database is much more comfortable :)
This link will bring you there:
Star Stable Database by Abbie Starwatcher