The Diamond Straight is an easy stitch to learn. It is comprised entirely of straight stitches. The pattern is: over one, three, five, three, one -- skip a row of holes, repeat. The tallest stitch of the second row lines up with the bottom of the smallest unit of the first row, one canvas thread to the right or the left (in the skipped row of holes).
After you have stitched the diamond units you fill in the empty spaces with Continental stitches in a complementary-colored thread. These fill-in stitches create a lattice pattern which nicely enhances and completes the diamond pattern.
When stitching a straight stitch over one canvas thread it is sometimes wise to do the stitch twice so as to avoid the dreaded disappearing stitch syndrome. A straight stitch over one canvas thread has a tendency to disappear. Doing it twice makes it more prominent. Try it -- see if you like it.