Sorry I didn't get back here sooner. Thank you for the nice comments
Pearl is correct, no sewing together for this, or I'd not have started it! You start the first square with a line of cast on, and then decrease in the centre as you knit the shape, and it becomes diamond shaped by the time you cast off the last stitch.Most of the diamonds are made by 'pick up and knit' along existing edges, and you weave in all you yarn ends as you go.
Not technically difficult, just took me ages, and I didn't knit it the summer much as you get too hot with all blanket in your lap!