The chest of colors is so nice! You got a great gift. I would certainly keep it. Cotton or poly. I have lots of Guttermann spools and they look small but really have a lot of thread once you see how thin the spool spindle is when one is empty. I'm not the least bit concerned if the thread is cotton or poly thread in my quilts. To me that is like being concerned if my child's eye color was blue or green.