How to instatinate RenderSettings in script?

Could someone show me how to save RenderSettings?
I wrote c# script below in vain:

  private RenderSettings originalRenderSettings;
originalRenderSettings = Instantiate(RenderSettings);

What is RenderSettings belonging to?

I think you 99% of cases want to use the static variables exposed on the class. RenderSettings belong to the currently loaded scene.

RenderSettings.fog = true;

I don’t think you should have more than one render setting per scene. Anyway, it is an UnityEngine.Object, so the following should work (but I don’t know what the expected behaviour of it would be).

// Every scene has a RenderSettings, so let's get it.
RenderSettings settings = Object.FindObjectOfType<RenderSettings>();

// NOTE! Now you get TWO RenderSettings! 
//       This will probably confuse the *heck* out of Unity.
RenderSettings clone = (RenderSettings )Object.Instantiate(settings); 

Or if you just want to create a new RenderSetting I think it’s just

RenderSettings newSettings = new RenderSettings();

If it has a public constructor…