andras:
If you want the material to have the same appearance for all Zones, but have a line between Zones, then Duplicate the Material and use the duplicate for one of the Zones, this will show the line between Zones.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David