If you take a cutting of a branch it will still be a BRANCH 20 years from now it will NOT become a tree. Spruce are propagated by seed & grafting ONLY!!!!

Grafting or air layering would be preferred methods to obtain more blue spruce.
Air layering can be done by scraping the surface of the Cambium, applying root hormone to it and wrapping the area losely w/ moist Spagnum. When that's done, cover the whole area w/ saran wrap secured by twist ties top and bottom.
Here is a good site to show different types of grafting methods.

Paul B.