A professional jeweler can determine proper ring size using a set of steel gauge-rings. These "ring sizers" come in narrow and wide widths. Other methods, such as measuring the finger with a strip of paper, or slipping the finger through pre-cut "measuring holes", are inaccurate. A wider band can be worn more loosely. Large knuckles/hands should wear a slightly loose ring, while slimmer knuckles/smaller hands will require a tighter ring. A good way for a "rough-and-ready" measurement is to find a ring that is just smaller than the second knuckle of the finger. This way the fit is comfortable but will not slide off the finger. The method of trying on a ring and shaking the hand violently, to see if the ring comes off. Tips: (1) Fingers change over the course of the day. It has been recommended that fingers be measured at the end of the day, when they are at their largest diameters. Heat makes fingers thicker. Cold makes fingers thinner. (2) Midda...