Definitive postage stamps of Ireland are the regular series of definitive postage stamps issued by the Irish Free State between 1922 and 1937 and by Republic of Ireland since 1937. Nine distinctly different series of designs have been released; additionally the watermark was changed for two issues and the currency was changed on three occasions while the designs remained the same.
The stamp series
First series
The first twelve stamps, the low-values up to 1 shilling, were issued during 1922–23 whilst the three high-values, 2/6, 5/- and 10/- did not appear until 8 September 1937. They were printed by typography by the Government Printers, Dublin on SE watermarked paper. The designs were: Sword of Light (4 values), Map of Ireland (3 values), Celtic Cross (2 values), Arms of the Provinces (3 values) and St. Patrick (3 high values). A small number of coils with either the horizontal or vertical edges imperf (straight) were issued between 1933 and 1935 including the rare coil in 1935.
Starting in 1940 these stamps were replaced by similar ones but printed on "gaelic e" watermarked paper. Two new values 8d (Sword of Light) and 11d (Celtic Cross) were introduced in 1949. In 1967/8 the 3d (Celtic Cross) and 5d (Sword of Light) changed to being printed in photogravure using a slightly smaller image. Two coil stamps, with imperf vertical edges were also issued.
In 1944 the 1/2d and 1s issues were replaced by the corresponding values of the set printed to commemorate the tercentenary of the death of Mícheál Ó Cléirigh designed by Richard J. King effectively becoming the definitive versions of these denominations for twenty years.
Gerl designs
Watermarked paper
Known after its German designer, Heinrich Gerl who won the 1966 international design competition, this was the first new design of Irish definitives in 31 years for the high-values and 46 years for the low-values. Sixteen stamps debuted between 1968 and 1969 on four release dates. The graphics were all based on early Irish art motifs: a dog was used in one colour for the low-values, the elk was used for the middle-value, the winged ox and eagle designs were on the high-values.
These stamps used the letter 'p' (Irish pingin) to denote pence rather than the 'd' (Latin denarius) used in the UK, so the three pence stamp bore '3p'. These stamps can be distinguished from the next issue by the presence of the letter 'p' after the numeral.
Decimal currency
With the introduction of decimal currency on 15 February 1971 the Gerl designs were reused in different colours and values and released between 1971 and 1974. A total of 18 single value stamps appeared plus three different multi-value coils; one 5p value and two different 10p se-tenant strips.
Since the previous series had used the letter p to denote pre-decimal pence, the stamps in this series just used a numeral to denote the denomination, so, a three-pence stamp bore the digit 3 with no 'p' after it.
Unwatermarked paper
The last of the Gerl definitives consisted of 14 dog designs, 9 elk designs and 6 winged ox and eagle designs issued on 17 different dates between 1974 and 1980. For the first time a £1 value was put on sale. Some of the values produced were to replace different values as needed because of changing postal rates due to inflation. Unwatermarked paper, that had been introduced with the 1972 Christmas stamp, was used for the first time on definitives.
Between 1981 and 1982, six more values, printed by lithography, were issued on four different dates. A multiple coil stamp based on a se-tenant strip valued 10p also appeared.
Architecture
Line drawings by Michael Craig with graphics by P. Wildbur were used for a new series based on Irish architecture through the ages. Over six dates between 1982 and 1988 twenty-eight values were released starting with a low-value of 1p and a high-value of £5. The images depicted: Central Pavilion (Botanic Gardens, Glasnevin, Dublin), Dr Steevens' Hospital (Dublin), St. Mac Dara Church (Co. Galway), Aughnanure Castle (Co. Galway), Cormac's Chapel (Cashel, Co. Tipperary), St Mary's Cathedral Killarney (Co. Kerry), Casino at Marino (Dublin), Cahir Castle (Co. Tipperary) and Busáras (Dublin).