Stretch 7/16" or 11mm:
A stretch is a jewel / piercing usually worn in the ear.
The principle is that a hole is been pierced and gradually increased by replacing the jewel by a larger one. Like many other habitudes from the Incas and several other African cultures this on has blown over to ours.
Kiuno distinguished by its innovative form. Which it is not traditional circular but triangular with a gun barrel cavity.