Each stone is wrapped in a fine silver bezel on sterling silver sheet. Adjustable sterling silver band. I would confidently say these rings can adjust up or down a full size but they may be able to be adjusted even more. I would just recommend choosing a ring in a size closest to one you currently wear.
The size you click from the options above will show you the picture of the ring you will receive.
Note: I would only adjust your ring once or twice until it fits the finger you want to wear it on. Continuous open and closing of the ring has the potential to stress the metal out and over a long period of time doing this could cause a fracture in the ring!