I introduced "diamante poems" by using the Read Write Think website. They have a couple of great examples and an explanation of how to set the poem up. You can even create your own poems online and print them out. My class warmed up with a few examples on the SmartBoard and then took the field to practice on their own.
Here is the link for the Read Write Think Diamante Poems.
Here is how a "diamante poem" is set up.