The Lark's Head Picot Join (LHPJ) developed out of a need to avoid a blip of color in a picot join. Two color tatting or tatting with ombre or variegated threads leaves a tiny spot of unwanted color showing. Lily Morales taught this to me back in 2003. I prepared this photo tutorial for the online tatting class in 2003.
The LHPJ looks just like the familiar luggage tag loop.
Bring the joining thread through the point of attachment, in this case a picot. Pull out a generous loop of thread.
Grasp the bend of the loop and fold it back on itself so that it look the way the luggage tag loop looks.
Take the shuttle thread through the loops making it look like the handles of the suitcase with a luggage tag attached. The pink thread is actually the black thread and is part of that ring. It is just shown in pink to help you follow the join.
Remove all the slack from the loop closest to the last regular double stitch tatted.
Holding the first half stitch firmly, remove the slack from the second loop and tighten.
Compare the two rings joined with the LHPJ. Note the one ring is larger by one double stitch. So you may need to adjust the number of the double stitches in a pattern or shift the join left or right in the pattern.