Glass has an incredibly smooth finish and is chemically inert (void of any chemical activity), making it an ideal material choice for your stretched piercings - this is especially true if the wearer is allergy-prone or sensitive to certain metals, as glass is completely hypoallergenic and biocompatible by nature. The smooth surface makes for easy wipe-down cleaning, and its non-porousness means that it will not collect and absorb bacteria like some other materials might. Glass can be very fragile, so it is best to remove these pieces whilst showering, swimming or bathing, and store them carefully when they are not being worn.