Although the vast majority of coins are round, coins are made in a variety of other shapes, including squares, diamonds, hexagons, heptagons, octagons, decagons, and dodecagons. They have also been struck with scalloped (wavy) edges, and with holes in the middle. Coins in the shape of polygons often have rounded edges or are Reuleaux polygons.
This article focuses mainly on circulating coins; a number of
non-circulating commemorative coins have been made in special shapes, including guitars, pyramids, and maps.[1]
There is a list with more unusual shapes of non-circulating commemorative coins at the end of this page, that all have been issued officially by various countries.
Indo-Greek coins were often square. Aruba has a large circulating square 50 cents coin.[3]
Many countries have struck square coins with rounded corners. Some of these, such as the Netherlands zinc 5 cent coin of World War II (1941–1943)[4] and the Bangladesh 5 poisha coin (1977–1994)[5] are oriented as a square, while others, such as the Netherlands 5 cents (1913–1940),[6] the Netherlands Antilles 50 cent, the Bangladesh 5 poisha (1973–1974)[7] and the 1981 Jersey 1 pound coin,[8] are oriented as a diamond. Ceylon (the current Sri Lanka) issued its first square coin in 1909, followed by several others.[9] India has had various circulating square coins as well, like denominated 1/2 and 2 anna coins,[10] as well as 1 and 5 paisa coins.[11]
siege money of Newark, was often in the shape of a lozenge
(rhombus).
Pentagonal
The
Mutawakkilite Kingdom of Yemen introduced pentagonal1⁄16 and 1⁄8 rial coins in 1948.[12][13] In 2014 Transnistria was the next country to issue a circulating pentagonal 5 rubles hard plastic coin.[14]
The Chile 1 peso and 5 pesos coins issued from 1992 to 2015 are eight-sided.[26][27] So was the old circulating Malta 25 cent coin commemorating Malta's first anniversary of the republic[28] and some California gold coins. Some other countries that have issued circulating octagonal coins are the Lebanon[29] and Sierra Leone.[30]
Nonagonal
In 1972 the first country to issue a circulating nine-sided coin was Thailand with a 1972 regular 5 baht coin,[31] followed by Kenya in 1973 with a special issue 5/= coin. The third and final circulating nonagonal coin issued in the 20th century and is the regular 1976 50 cent coin from Tuvalu.[32] Currently, the Philippines issues nonagonal 5-peso coins from 2019 as an enhanced design of the round version to make it distinct from the other denominations.[33]
Decagonal
Hong Kong issued a
two piso (peso) coins from 1983 to 1990.[35] Some other countries that have issued ten-sided circulation coins are Chile,[36] the Dominican Republic,[37] Jamaica[38] and Madagascar.[39]
Hendecagonal
The old
Canadian one dollar coin is an eleven-sided Reuleaux polygon.[41] Also Madagascar has issued some circulating eleven-sided coins.[42]
In 1993, the Czech Republic was the first country to issue a 13 sided20 koruna coin.[51] In 2013, Tunisia followed with a 13-sided 200 millièmes coin.[52]
Pentadecagonal
A 5 dirham commemorative coin from the UAE in 1981 had