You could sue the pawn shop for negligence.  Negligence is the failure to exercise due care (that degree of care that a reasonable pawn shop would have exercised under the same or similar circumstances to prevent foreseeable harm).Your damages (the amount of compensation you are seeking in your lawsuit for negligence) would be the value of the ring.  Depending on the value of the ring, you might be able to file your lawsuit in Small Claims Court.  Your damages would include the value of the ring and court costs.  Court costs would include the court filing fee and process server fee.