Here are some wedding rings I have photographed on some of my weddings. I typically use the 105mm 2.8 macro / micro lens to get really close, especially when the inside of the rings are engraved. Sometimes I use the 35mm 1.4 prime if I want to focus on composition. When it is too dark and there is little light to focus, I get my assistant to point a torch or video light on the rings. Depending on the available light, sometimes I use bounced flash instead.