They were craftable at one time by tinkers. 2000ish? You sometimes see the bugged versions like "50000 diamond weddingband", at first you could target a stack of gems, then they changed it to just one. That is also the origin of the tree ornament weddingband. I think they did away with them when they introduced the Magic Moments program and you got custom wedding rings. Prior to the weddingbands, you had to get married by someone from the Interest (seers, troubadours) team to receive a ring. If it is a newbified item, you won't be able to lock it down. But pick it up quick as it will decay in 15 seconds on the ground. You can, however, lock a container down and put it in the container and it will lock down.