Can anybody tell me, the name of the default folder icon used to display standard folders in kde? I looked in some icon theme packages but I m confused:

What are the folder_blue.png, folder_red.png, folder_green.png, folder_cyan.png, folder_yellow.png and ...open.png aso for? I never met any of those but the blue one.

I tried to change the default folder icon by replacing the folder.png or folder1.png files in every size folder, but it did not work. Do I have to replace the folder_blue.png´s?

Is there any howto explaining what folder icons are used for what purpose?
Please help.

The best place to look for that kind of info is kde-look