SWG and AWG are wire gauge systems and are used to represent the thickness of the wire in jump rings. Different numbering systems are used, depending on the type of metal.
American Wire Gauge System (AWG), sometimes called Brown & Sharpe, is generally used for precious metals. Specifically for non-ferrous, meaning not-containing-iron, metals. All the sterling and niobium rings Blue Buddha Boutique sells are measured using AWG.
Ferrous metals generally use Standard Wire Gauge (SWG), also called Imperial Wire Gauge or British Standard Gauge. All the base metal rings Blue Buddha Boutique sells are measured using SWG, except 20ga and 22ga base metal rings, which are AWG. (Base metal = aluminum, copper, jewelry brass, bronze, stainless steel, enameled copper, anodized aluminum.)
Overall as the gauge number decreases, the thickness of the wire increases. In other words, in the same metal, 20g is thinner than 18g which is thinner than 16g. Because gauge systems can be somewhat arbitrary, many serious maillers prefer to use wire measurements instead of gauges so that others know exactly what the wire size is.
Please refer to the Wire Gauge Conversion Chart toward the bottom of our Jump Ring Sizes page for a listing of the exact wire diameters for the rings we sell.