I find the colourful Zen garden most beautiful!
Before I presented the coloured sand jars which were filled with coloured salt. If you use a plastic plant you can use this for the modern Zen garden, too :)
Links:
Modern Zen Garden (Less Work More Zen VI ( Modern Zen Garden ))
via: modern zen gardens {objects of desire}
via: DIY: zen gardens
Here at unikatissima:
Coloured Sand Jars