Locked Footrope/diamond Knot
The footrope/diamond knot is attractive but can loosen when handled, especially with synthetic slippery cordage. By using the over two crown knot this problem is eliminated.
After tying the last regular crown knot bring any cord over two adjacent cords (instead of one).
Do the same with the second cord
Do the same with the third cord going through the bight of the first cord
Do likewise with the next cord going through two bights. Tighten, If you wish you can stop now and the last crown knot will remain locked in place.
Repeat steps 1 - 4 without tightening completely. Bring any cord under the adjacent cord and up through the center passing under 2 cords (crossing point)
Do the same with the second cord
Likewise with the third cord
and finally with the fourth.
Grab the four ends together in one hand and slightly tighten the knot by grabbing the body of the knot in the other hand and pulling apart. Tighten.
Cut the ends. This technique works equally well with the cobra stitch/solomon bar.