From: "Roger R Degner" rog781@means.net
    Date: Sun May 14, 2006 2:46pm(PDT) 
Subject: Re: Case coloring

If you just want colors and no case hardening, buff or file the surface
to bright metal.  
With a torch that has a pencil tip (small intense) begin heating a 
small
area.  First you should see a yellow or bronze then peacock (purple)
then blue. Have a wet rag handy to stop the colors by cooling.
Keep playing to get different effects.
You can buff out a color you don't like with a dremel tool

Practice on a piece of scrap metal several times before doing something
to a voluble item

Roger R Degner