Prepare two round leather pieces with a diameter of about 1.6 cm, a Jump Ring, a Beaded Key Chain, and a spot mounted with Genuine Gemstone with a diameter of 7 mm.
Here we use the LeatherCraftTools.com's product "Leather Tag (Round Shape S) ".

Check the position of the prongs, and make small holes.

Carefully bend the prongs using pliers.

Fold it as much as possible, being careful not to scratch the Gemstone.

Apply bond to the backing leather and stick the leather together.

Apply finishing agent on edge for better finish.

Open the Jump Ring with pliers, pass it through the round hole in the leather, and then close it tightly.

It is completed through the Beaded Key Chain.