A rai stone (Yapese: raay), or fei stone, is one of many large artifacts that were manufactured and treasured by the native inhabitants of the Yap islands in Micronesia. They are also known as Yapese stone money or similar names.
The typical rai stone is carved out of crystalline limestone and shaped like a disk with a hole in the center. The smallest may be 3.5 centimetres (1.4 in) in diameter. The largest extant stone is located on Rumung island, near the Riy village; it is 3.6 metres (12 ft) in diameter and 50 centimetres (20 in) thick, and weighs 4,000 kilograms (8,800 lb).