You've seen rings opened and closed using two pairs of pliers. Some people prefer to use one pair of pliers and a ring opener or jumpring tool, especially for opening a number of rings at once. The ring opener fits over the forefinger of your non-dominant hand and one side of the ring is fitted into the appropriate sized slot. While braced in this position, the pliers in the right hand are used to twist the ring open or closed, as shown in this photo. Some people find this method awkward, but those who prefer it really love this tool and become extremely handy with it.