With my shortened pearl pins (see previous step of this tutorial), I will place them down the front of the boutonniere, pinning the diamond wrap into place.
Push the pins into the taped stem, making sure they do not extend out the back of the boutonniere.
Continue down the stem, piercing the band in between the open spaces of the wrap.
Here's a side view. The band is now secured to the front of the boutonniere and will not come off it.