I've been studying color theory and how I can make use of it in the designing of clothing, jewelry, and various accessories with a Steampunk bent (and in general). These are my observations.
This article is free for download and re-distribution, though if re-published I prefer that I am contacted and referenced. Thank you, and I hope I've helped others in their art!
UPDATE: By the by, I found this as a beautiful reference. The site displays antique arms and armor, with this page being for swords. It displays the vast array of colors you can see in metals due to different curing methods. There are some really great examples of bluing here, for instance, as well as some browned pieces: [link]