There are no current or past technologies that make stainless look like a blue carbon steel firearm. If that is the look you like, then you need to buy a modern carbon steel firearm like these model 27s.Smith and Wesson has been using IONbond for more than a decade now. The IONbond finish that S&W uses is a black looking finish, not blue.
I am not aware of the folks at IONbond offering a polished version. I just reviewed their website again and see no mention of this option
IONbond does looks different if applied to a surface that was prepared with a brushed vs. matte vs. polished finish prior to application. Is that what you are referring to?
This Pinto 627 is about 13 years old. The 627 was prepared with a more polished finish while the TRR8 pictured below it was not. The difference is not that great
Ionbond does not offer polished, brushed, or matte anything, all they offer is a coating service. Your gun needs to have the metal prepped before it is sent to Ionbond to be coated with their DLC. The prep can be done by your gunsmith, if he knows what Ionbond requires, or it can be done by one of Ionbond's agents like Evolution Armory, Palmetto Arms, or Jabuie. You have to use one of their affiliates to get your gun to Ionbond for coating, you can't send it in directly anymore.
Now that that is out of the way... Yes, Ionbond DLC can be applied to polished stainless steel and it will look very much like dark bluing. As far as I know it is the only black coating that will let the polish show through, everything else has a texture of it's own. When metal is coated with DLC it must be completely clean and free of any other coating, even bluing. My 1911 is carbon steel, but when it went in to Ionbond it was totally bare, "in the white", and when it returned it was ink black. Stainless steel would look the same way.
Before it was coated by Ionbond -
After, jet black -
For comparison, this 1911 has been polished and hot blued. This picture was taken the same day, at about the same time, I chose this one because the guns are in similar positions. As you can see in the same lighting, same camera, etc, the polished Ionbond DLC gun and the polished blued one look very very similar.
Most modern bluing is blacker than it used to be, Ionbond DLC over polished stainless is about the only way to get a stainless gun to look similar to bluing.
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