The blocks are set on point, and each block has a triangle sewn on each side to make a larger square block. The quilt is paper pieced, with 18 inch long borders being sewn on the end of each horizontal row. If sewn together on a diagonal, the borders would have to be sewn together before being added. This is hard to understand without a picture, which I don't know how to post. You can see the pattern and maybe understand better. Pattern is V235, Carolina Lily, at "averyspecialcollection.com". It's really a beautiful quilt. All pieces are done, ready to put together. Maybe I'll learn how to post a picture by the time I finish it. Thanks for all the replies. I learn so much here.