The single strand diamond is a nice stopper or ending knot.


Single Strand Diamond Knot tutorial
I thank the Soylent branch of the IGKT for introducing me to this knot

Bring Working End on the right in a loop over itself.


Make another loop on top of the first


Bring WE from right to left over, under, over, under


Bring WE over to the right over the standing part


Bring WE to the left over 1, under 2 and up through the middle


Take the slack out slowly.  DO NOT try to tighten the knot in one go.