Here’s how to do it
1) Iron all sides of the fabric at your desired hem width.
2) Fold the hem over again with the same width and iron.
3) On the corner, unroll one fold of the hem.
4) Fold the corner in diagonally. Align it so the fold creases made from the iron in the previous step match up with the width of the first fold of the hem. Iron the corner down so it makes a diagonal crease in the fabric.
5) Mark along that diagonal crease with chalk or pencil or fabric pen.
6) Fold the fabric over and sew along the marked diagonal line.
7) Trim off the corner, leaving about 3/16” seam allowance.
8) Flip the corner right side out. Use a point turner or some other pointy object to press out the corner.
9) Edge stitch along the inside edge of the hem.
10) Enjoy the beautiful corners with all the extra care and love you put into creating them.
This lovely lightweight linen fabric is from Fabrics-Store.com. I enjoy sewing with their fabric. They have a wonderful selection of linens in various weights and colors. Not to mention they are a family company, and their blog is amazing.