I had copy some pages from an old Luger book that has some details of the different temperatures and the color the different heat treat produce, such as straw, blue, purple-blue, etc... It also goes into some details about rust blueing; this takes anywhere from 4 to 7 days to complete, depending on the humidity. Anyway, if you're interested, I can did it up and post a summary here.
Thong
Thong