Here is what you will need:
The clay needs to be about the thickness of a ten-pence, and the size somewhere in between a ten-pence and a fifty-pence. You can alter the size to your needs, say if you make earrings.
Craft knives are recommended for cutting clay, as they are sharp and won't tug the clay out of shape.
My dad does own a piercer with his craft knife set, but I couldn't be bothered to use it ;) a cocktail or kebab skewer works just as well. Be very careful when lifting the shaped and flattened disc of clay from the board, as it can pull out of shape.
Bake your clay according to the instructions on the packet. Skip if you use air-drying clay.
Washing your hands is an important step in using clay. It removes any clay from your hands, preventing you from ingesting any and getting sick, and it also prevents colour transfer from your hands onto the clay you are now handling. This is especially important when handling both light and dark clay.
Don't rush this step, otherwise you'll end up with a messy pendant. A thin brush is recommended.
I forgot to add images of this, but here we go.
You're going to have to bend open the tiny ring with the pliers. Then , thread it through the hole you made in the clay. Finally, push the necklace chain inside and use the pliers again to close up the ring.
Enjoy your necklace!