It appears to be glass, but the details are unknown. Please consider this before purchasing. This was received as a souvenir from overseas. Size: Approximately 1.2 cm in diameter *Approximate size (measured by an amateur) There is a hole in the center. The color may differ slightly from the photos. There are also some blackish parts. It has been stored at home for a long time, so please refrain from purchasing if you are concerned. (It's quite old) Please check the photos carefully and consider thoroughly. Price reductions will be made at my discretion. #eijewelryaccessories Mercari exclusive