margecam52

The little dots they have you mark...those are seam allowance dots...On the back of one of the diamonds, use a ruler to mark a 1/4" pencil line along the long sides of the diamond...go all the way to the edge...mark lightly so you don't stretch the fabric. The lines will cross at the sides and tips...The exact spot where they cross...that's where the diamond 1/4" seams should line up.
I find this marking of the stitching lines to give a better result than just marking that dot.
I mark all the diamonds on the back with the stitching line.
Remember, when you line up the dot/crosspoint (depending on how you do them)...the tips of the diamonds don't line up exactly...they should overlap 1/4". You start stitching in the "v" of where the tips stick out...and that should put your needle right on the lines you drew, stich an inch or so, stop and check the line on the underside piece...adjust if not being stitched on.
Yes, it takes a lot more time..but results in a perfect result every time. I now sometimes will do the center part (which is a lemoine star, by the way) without lines drawn...I can now eye what the 1/4" overlap should be. But if I do that throughout...I end up a bit wonky.
Look up how to do a Lemoine Star...that will help with all the diamond construction in this pattern.