I've had several (two) requests for this pattern, so you non-knitters, just chat amongst yourselves whilst I elucidate. This not a real step by step pattern, so you must figure out your own yarns, gauge, needles, swatches etc. Be brave and try stuff! This design works with any yarn combo, or even one color (boring). I usually use size 8 needles and worsted or dk or a combination of both, or either. 31 stitches for triangles and 63 for the diamonds. The side panels are where you can figure your needed dimensions. More rows equal wider inches. Simple. Sometimes I use size 9 needles for the side panels.
I begin with casting on 3 stitches and make the first triangle, #1, increasing one stitch in from each of the edges, front side only. In this instance, I arrive at 31 stitches and then I begin the second triangle #2 by decreasing on the left side only, until the stitches run out. Cut yarn and begin triangle #3 by picking up stitches along #2. Decrease on right side only until stitches run out. Do not cut yarn. Make #4 by picking up stitches along #3, decreasing on left side, cut yarn and begin on #5, decreasing on right side.
Second front panel is the same only reversed.
The ruler is placed where triangle #1 ends and #2 begins. The blue yarn is always the color to begin.
The back is done similarly, with two beginning triangles, #1 knit separately (31 sts.)and then #2 is knit (31sts). Joining them begin diamond #3 and add one center stitch for a count of 63 stitches. Diamond #3 is made with decreases over the center 3 stitches, so it pays to mark those until you can recognize where to do decreases on following rows. Decrease: Sl1, k2tog, psso. For triangle 4, pick up stitches along #3 and knit them as you did on the front panels. For triangle #9, decrease in the center 3 stitches as usual, but also decrease on each edge until 5 stitches remain. Bind off.
Pick up stitches for side panels, connecting front and back tops with knit markers or tie the two end threads together. This is just to keep them in place until the side panel is knit. I don't count how many stitches I pick up along the front and back panels, but you can if you seriously want them to match.
After I finish the panels, I sometimes go back and add a teeny triangle to round out the hard neckline angles of the meeting panels. It varies every time I do it and you might figure out a nice way for yourself.
Looks ok here, I guess.