Since online jewelers make custom order rings, it is possible to get a ring from a school you didn't attend. Order college rings, and choose the school that is going to be written on the ring, regardless of if you went there or not. When you go online to make your ring, you first pick the design, color and the stone shape, size and color you want.
After choosing the basics, you proceed to customizing the ring itself. You can pick a picture, such as your mascot, to go inside the stone. You can also pick logos or script to go on the sides of the ring; these usually highlight your interests or major at the school. These get engraved on the side of the ring as well as your name and graduating year. On the top of the ring goes the school name that you type in -- meaning you can pick the school that is going to appear on top.
Because you get to pick the school, the website has no way of knowing if you actually went there or not. You can pick any school and make the ring your own or a gift for someone who did go there. After picking the school name, you can have your name engraved on the inside of the ring as well as a small logo depicting a club or group.