I don't know - sorry - but wonder how in the world that a quilter sewed on so many on a quilt that I saw in Paducah at the Quilters Museum a few years ago. All of the quilts were fastened/displayed on the walls - but one spectacular quilt was just hanging from the ceiling and had ropes around it so that you could walk around it. That is because, sewn on the back were 120,000+ Svorski crystals!!!!!
Yes, it was almost unbelievable.