You cut the center portion out of the leaf but instead of cutting it into sections, you leaf it whole.
You wind it around to form a cone and insert into your rooting medium. Make sure to also put some medium inside the cone. On the page are illustrations showing how to do this.
The advantage to cone cuttings is the full plants you can get from this type cutting.
Plantlets will come up from all the vein ends along the bottom of the cone resulting in dozens of shoots.
If left together, they quickly grow into one full plant. They can also be separated or cut apart to make many smaller plants after rooted and plantlets have formed.
On all the various leaf cuttings discussed in this section after plantlets have formed you can either pot up the cutting along with the plantlet or you can remove the plantlet and use the cutting over again.
Some cuttings will send up plantlets several times before they run out of energy if reused.
Credits / references:
Brad Thompson | Brad’s Begonia World