Feed raw egg white for the next 24 hours. Depending on how large this piece of jewelry is whether it will pass through the gizzard. If it does, expect it to look like it was run through a garbage disposal when you get it back.
Ask to see the x-rays. This may not be the only hardware this hen has consumed. If you find she has swallowed other metals, she probably has a condition called pica. This affects animals and humans alike where non-food items are consumed obsessively. When a chicken has this disorder, they eventually die, often of metal poisoning if not starvation from being blocked by a lot of metal in the digestive system.
Since learning about this condition, I meticulously pick up screws, nails and staples as I work. The same goes for string and yarn. You wouldn't believe how much damage string can do to a chicken.