Frocktalk posts a very interesting interview with Michael O'Connor, costume designer of Jane Eyre 2011 in which he says thinks like this:

Tell me about how you arrived at the color palette.  It was exquisite.  Was it a result of conversations with the Production Designer and DP, or was it something the director had in mind?
The colour palette really is about the balance between Jane and other characters. The book often describes Jane as wearing plain black. I thought this would be too severe so chose shades of grey, dark blue and slate colours with subtle patterns to reflect the mood of the scene. Once these colours were established, other characters fit in around her. So, for example Rochester has a brown frock coat and not the more usual black; likewise Mrs. Fairfax is mostly in brown. Blanche Ingram, where the temptation is to be brash and colourful, could be designed more subtly. bronteblog