as long as when you do a (tug-test) and the thread does not break you can use it for piecing- it does not have to be any particular kind of thread- many people piece with poly threads, or poly blends ---some peice with cotton thread-
i prefer silk- but that's me-
rayon is another option- there are many threads out there
get what is strong- the color is what you want and the weight is what you want.