It'll work on the diamond, but this theme is for WVGA resolution devices and the diamond is smaller (VGA I think), so you'd need to resize all the images in the theme for a VGA screen instead.
Sorry man, I only have a wvga device to work with, but feel free to take the theme and resize the graphics for your phone. I'm gonna be moving to android soon, so won't be working on wm themes anymore.