It is made of a heavy plastic, I would say unbreakable and more sturdy than regular plastic. It isn't ceramic or glass. I have used one (the one in this listing is brand new, never used, I had kept 1 for myself) for a few years. It hasn't been damaged from the dishwasher or from being dropped. I've left drinks in it for a time before rinsing it out, and it hasn't stained (the inside is white). Let me know if you need me to clarify. I can look at the bottom of the glass for you, as these comments are from my experience.