This page has photos of actual 19th century garments, which I find useful for inspiration.
Most of these photos were found on eBay and antique garment dealers, like: Maire McLeod Elegant Vintage • Karen Augusta Antique Lace & Fashion • Antique & Vintage Dress Gallery • FiddyBee • Time Travelers • 1860-1890 • Rupert & Toby’s Collectables • Carolyn Forbes Textiles & Vintage Fashions • Old Threads Antique Textiles.
Another site with lots of excellent images is Démodé: Extant women’s clothing 1750-1919.
Click on thumbnails to view larger images.
Lavender silk gown, c.1870 images courtesy of Maire McLeod Elegant Vintage