Comment 57 for bug 651678

The easiest workaround (and the cleanest hack) is to just add the line "Inherits=hicolor" to "/usr/share/icons/default.kde4/index.theme" (just open it as root via kdesudo kate), for example before the "Example=folder" line.
This will make all GNOME apps find the right icons if KDEs Oxygen style is used.