A very interesting use of the Spike Stitch. No link to a pattern, but the photo is clear enough to see how it is done. My guess is 6 stitch repeat, 3 rows of SC. On the next row, start with 1 HDC, then do gradually longer spikes, first the stitch, next one below the stitch, etc., moving down each row. The pinner said HDC spikes were used. For the diamond effect, the next 3 rows of SC are the same color as the spike stitches below. Can't wait to try this.
I've had a photo of the spike stitch over at a Pinterest board of crochet items I wanted to make. I had wanted to try this and yesterday ...