How to set themable folder icon in GNOME3

In all systems, be it Windows, OSX or Linux, You can set folder icon in files explorer by selecting an icon in a properties window. But Linux encourages You to change system theme. If You want to use themable icon for a folder, which will change with a theme change, you can use gio command. For instance, if You want to have second documents folder, use the following command:

gio set <folder path> metadata::custom-icon-name "folder-documents"