I use various colors of hand quilting thread all the time. I just finished a baby (boy) quilt and used a combination of red and blue thread - separate colors in different blocks. I wanted a bit of variety. Intentionally, some of the quilting is obvious and some not so much. The backing on this quilt is a crazy, all over design to coordinate with the front. The stitching is not as noticeable on the back but I'm good with that.