Something I'v been doing for a few years that comes out looking very simular to case coloring is to guench the part in an un-heated "hot caustic" blueing satls solution. It doesn't get the part as britel as cold water and the color of the part is motteled blue/brown/gold. With a little practice parts come out looking very nice. The solution I use is about a 50/50 hot tank solution and distilled water. Un-heated "hot salts" are usually a heavy sludge with a thick hard crust on top. Thats why I diluted the solution to 50/50 so it stayed in a liquid form.
