Why knotting pearls in the first place?
Let us start with the traditional way of keeping your pearls in perfect shape. To avoid losing your pearls jewelers knot their expensive strings of pearls. When the cord breaks you only lose one of two pearls and not the whole string. That is if you notice losing your pearls, otherwise, the whole string is gone.
Besides the reason to prevent losing your pearls the knot is a kind of buffer so that the pearls don’t rub against each other. The nacre of the pearl is precious and soft and when the pearls hit each other all the time the nacre comes off. And a knot between each pearl prevents this.
This is the way knotting works: https://youtu.be/wjjKy5aBsws?t=6
This pearl choker necklace is not knotted since the used pearls are strong enough and will not damage each other.