Sometimes it's even hard to tell which is the right side, which is the wrong side to start with. I was told to look at the selvage, and the pin marks should be UP on the right side. Sometimes that's even hard to tell. I recently worked with a metalic lace, boy, that was hard! I flipped back & forth, trying to match by the shinyness, and after I sewed the seams, it didn't look right; so I ripped, and ripped and ripped. sigh! I am hoping that they are all right, now. lol