Such clam shell rings are used as means of payment by the Abelam people in the northeast of Papua New Guinea. They are called "yua," which means nothing else than clam shell ring in the Abelam language. In a slightly different form and size, shell rings are used as traditional money also among the Abelam's immediate neighbors. All rings larger than four centimeters are accepted as money – whether they are flat or bent, translucent or opaque. It is for this reason not really amazing that glass rings imported by the Europeans are also accepted as means of payment. There are differences of value between the single rings, but their estimation in general depends on individual considerations; a fixed scale of value does not exist.