I just started re-reading War and peace, having completely forgotten it since the first time I read it. And I'm noticing that Tolstoy is referring to clothing every now and then. I wonder what it actually looked like.
Looking up the history of clothing in Wikipedia, I note that this period (1805 to 1812) was dominated by Empire style fashion, which is quite different from most periods before and after. But of course the fashion in the different countries was different, and maybe it was not adopted in Russia. On the other hand, the Russian aristocrats were imitating the French ones (about a third of the dialogue seems to be in French), and maybe they were wearing full French fashion too. The Russian translation of the Wikipedia article doesn't help, as it only depicts Western examples of the style.
I noticed a few mentions of clothing which are consistent with Empire style, but not conclusive. One young girl is said to have naked shoulders, "as was usual then". A female figure has a reticule, and a male one a redingot. Natalia Rostova is wearing a sheer muslin skirt (кисейная юбка) and her lace drawers are visible the first time she is introduced, but this could simply be children's attire. There are also more baroque clothing items mentioned, for example a man wearing a jabot.
Should I imagine the figures wearing kiddie-pool-sized crinolines, or diaphanous gowns, or something else entirely?