Regarding ring sizes, we have listed the inner diameter. (As we are unable to prepare tools to measure ring sizes, there may be some slight errors. We appreciate your understanding.) Ring. ◎ Material: Unknown, but we believe it is an imitation material. ◎ Metal fittings have a SILVER G stamp. ◎ Inner diameter: Approximately 17mm (Approximately size 13) ◎ There are scratches, discoloration, and dullness.