Originally Posted by Monstookie
I would use purple for the back and then depending on the type of quilting I wold change the color of the tope thread to match the section I am working on. But I am not an expert.
This is what I do when I quilt quilts for myself as well as for customers. If you have problems with bobbin thread showing on top or top thread showing on the backing and can't get the tension balanced perfectly (can be a PITA), the match your bobbin thread color to the top thread color so you hide your tension problems. I also usually use variegated thread on the top. I use King Tut for my top thread and Bottom Line for my bobbin thread - both by Superior Threads.