Rai stones are large, circular stone disks used as a form of currency by the people of Yap, an island in the Federated States of Micronesia. These stones can weigh several tons and are made from limestone, which is quarried from nearby islands. Their value is determined by size, craftsmanship, and history, rather than their physical presence. The use of Rai stones dates back centuries and reflects the unique cultural practices of the Yapese people. Transactions involving Rai stones often occur without moving the stones themselves; ownership is transferred through verbal agreements, emphasizing the social and communal aspects of their economy.