This is a 3mm faux suede leather cord in a Turquoise color.
Use the scissors tool that is very sharp and great for cutting leather.
You only need 7cm of cord, and cut the edge of the cord in a diagonal line so it will go through the links easily.
Slide the cord through all the links of the chain.
You want the edges to be closed on the back side of the earring, so slide both ends through the last loop of the chain.
Cut away the extra cord, and use a bit of glue to hold the edges together.
Now choose a crystal, embed it into the stone setting, and you're done!
Have fun creating!