Quilted geometry

A few years ago my mom began work on a quilt for my wife and me.  I had the opportunity to design it, and went with something less common than the right triangles and squares you see on a lot of quilts:
quilt design copy
This is an example of an Islamic tile pattern featuring 5- and 10-pointed stars. 
Getting the pieces cut out proved to be challenging.  After some puzzling, I found that the design could be created using two rhombus-shaped “stamps”:
quilt design copy2
You could estimate the lengths involved, but exact answers are so much more satisfying.  I can’t quite remember how I went about calculating the proportions, but I was happy to find the golden ratio Φ featuring prominently in them:
It turned out pretty cool, don’t you think? 

But I hope you’re not in a rush to get yours – the hand quilting takes a long time.