When naming systems at Curbstone, we select names that relate to rocks, stones, or elements.  Our name refers to the borders of the streets that control and direct traffic, curbstones, just like our software controls and directs credit card traffic on your IBM iSeries, AS/400, or System i.  Researching for a unique name, we found this interesting monetary history.

Rai on YapThe official currency of Micronesia is the US dollar, but the island state of Yap uses an additional form of money: limestone discs, some of which weigh more than a car.

Rai, or stone money (Yapese: raay), are large, circular stone disks carved out of limestone formed from aragonite and calcite crystals. Rai stones were quarried on several of the Micronesian islands, mainly Palau, but briefly on Guam as well, and transported for use as money to the island of Yap. They have been used in trade by the Yapese as a form of currency.

Rai stones are circular disks with a hole in the middle. The size of the stones varies widely: the largest are 3.6 meters (12 ft) in diameter, 0.5 meters (1.5 ft) thick and weigh 4 metric tons (8,800 lb). The largest rai stone is located in Rumung island, near Riy village. Smaller rai stones might have a diameter of 7-8 centimetres.

Centuries ago, Yapese explorers journeyed 280 miles west in bamboo canoes to the island of Palau, where they encountered limestone for the first time. After negotiations with the people of Palau, the Yapese established a quarry, using shell tools to carve disc-shaped stones they named “rai.”

The stones varied in diameter from a few inches to 12 feet, and weighed up to 8,000 pounds. A hole punched into the center of each disc allowed the explorers to carry the larger stones toward their bamboo canoes using poles. Maneuvering the rai into the boats, and keeping afloat during the long journey home, was a much more treacherous undertaking.

Back on Yap, rai became a sort of currency, exchanged as part of social customs such as marriages, political deals, and inheritances. The value of each rai depended on its size, but also on its provenance—if explorers died during the expedition to retrieve a stone, it acquired a higher value. A transaction did not require the physical exchange of a disc, merely the acknowledgement of a transfer of ownership. In fact, one of the rai stones in active circulation sits on the bottom of the Pacific Ocean, having tumbled from a canoe during a storm on the way back to Yap. Islanders agreed on its value after hearing the story of how it came to rest on the ocean floor.

Though its appearance differed from other forms of currency, rai was not immune to the issues of your average economy—such as inflation. During the 1870s, an Irish-American adventurer named David O'Keefe accompanied the Yapese to Palau, where he used imported tools to carve the limestone. His methods sped up the rai production process, with negative consequences: Yapese placed a lower value on his stones than on the discs carved with traditional shell tools, and the sudden abundance of rai brought down its overall worth.

The quarrying of rai stones ended at the beginning of the 19th century, but the Yapese still exchange discs to commemorate traditions. Many of the 6,500 remaining rai are displayed in rows at outdoor “banks”—jungle clearings and village centers. Theft is not a concern.

Yapese stone money 2007While the monetary system of Yap appears to use these giant stones as tokens, in fact it relies on an oral history of ownership. Being too large to move, buying an item with these stones is as easy as saying it no longer belongs to you. As long as the transaction is recorded in the oral history, it will now be owned by the person you passed it on to—no physical movement of the stone is required.

The extrinsic (perceived) value of a specific stone is based not only on its size and craftsmanship, but also on the history of the stone. If many people—or no one at all—died when the specific stone was transported, or a famous sailor brought it in, the value of the rai stone increases by reason of its anecdotal heft.

Rai stones were, and still are, used in rare important social transactions such as marriage, inheritance, political deals, sign of an alliance, ransom of the battle dead or, rarely, in exchange for food. Many of them are placed in front of meetinghouses or along pathways. The physical location of the stone may not matter—though the ownership of a particular stone changes, the stone itself is rarely moved due to its weight and risk of damage. The names of previous owners are passed down to the new one. In one instance, a large rai being transported by canoe and outrigger was accidentally dropped and sank to the sea floor. Although it was never seen again, everyone agreed that the rai must still be there, so it continued to be transacted as genuine currency. What is important is that ownership of the rai is clear to everyone, not that the rai is physically transferred or even physically accessible to either party in the transfer.