Thanks for getting back to me.
I found this online:
You can color stainless steel, but it is not a process that is typically performed in a plating shop. The basic process, which was developed by Inco (International Nickel) in the 1970s, is to immerse the stainless steel in a chromic and sulfuric acid solution at a temperature just below the boiling point of the solution. A thin layer of chrome oxide forms on the stainless steel, and by controlling the thickness of the oxide layer you can obtain colors that vary from bronze to blue, gold, purple and green. After treatment in this solution, the stainless steel is rinsed and given a cathodic treatment to harden the oxide layer. The layer can vary from 0.02 µm to 0.36 µm; the thicker the layer the darker the color. Most commonly, 304 grade stainless steel is used. The coating is reasonably robust but will scratch.
ARTHUR S. KUSHNER
Blueing or blackening like they do for guns. Blackening is often called black oxide and they do tools as well. Parkerizing is a version for guns I think.
There is an older process called browning they used to do on guns, but I don't know much about it.
Finally, I've heard of people heating the steel red hot and then dipping in used motor oil to get a neat effect.
I guess you know heat will make a neat gold blue purple rainbow effect on shiny steel, but it comes off easily. You might clear coat it.
Other than the above, you're probably looking at plating or paint.