Ring Clamps are a great tool - especially for silversmiths and metal work. Holds your ring nice and firmly with out damaging it, whilst you sand, file, buff or polish it.
Simply open up the clamp, which can be used at either end, slip you ring into one end, and then push the wedge up into the other end to hold tight. One end of the clamp if rounded, and the other is squared and both have leather lining on the inside of the jaw to help protect your work.
6" (15cm) in length