Pearl strands are knotted so that the individual beads don’t rub on each other and damage the pearls. Over the years, I have come across and shared many techniques for knotting pearls, with or without tools. See links below for more.
This one from @hownu1 on Youtube has got to be the easiest I have seen so far! You’ll have to find cord that is fine enough to go through the bead twice for this technique.
