Ring Stretcher For Resizing Rings. This is a ring stretcher. This precision machined device provides an easy way of stretching stone set rings without loosening prongs or stressing stone settings. This ring stretcher comes with an assortment of 16 rollers which will accommodate most ring styles. Highly polished and hardened rollers eliminate the necessity of repolishing ring shanks after use. The smallest ring size this will work with is a size 5. This set comes in a wooden box that measures approximately 8 3/4" x 5" x 4 1/2" (222 x 127 x 114 mm).