The one pound (£1) (Irish: punt) coin was a coin of the Irish pound. It was used in Ireland from 20 June 1990 until Ireland joined the euro in 2002. The last issue was in 2000. The coin was the largest Irish coin since decimalisation: its diameter was 3.11 centimetres (1.22 in) and its mass was 10 grams (0.35 oz). The coin was almost identical in dimensions to the old penny coin that circulated until 1971, and was similar in diameter to, but thinner than, the half-crown coin. The edge was milled, and a dotted line ran along the edge of each face. Unlike some previous Irish coins, it was very different from its British equivalent, as the Irish pound separated from the British pound in 1979.