If during knitting you need to change the yarn or replace it with a new skein, and you want to do it as discreetly and naturally as possible, then take a closer look at this idea! With it, you can knit the two ends of the yarn as if they were from the same skein.
The photo below specifically shows an example on two contrasting threads. Lay the thread one on top of the other, criss-cross.
Wrap the lower one around the upper one and bring it up. You should get a node like this:
Now make the same knot on top. The lower thread is thus brought out to the left, and the upper thread to the right.
Now, at the same time, pull both threads in opposite directions, pulling two knots into one. Pull harder, trying to make a very tight knot.
Cut the ponytails with sharp scissors as close to the yarn as possible.
Here's what happened! Thread, as if from one skein of yarn!
For more information on how to connect yarn into an invisible knot, see the video below: