Overview
The opal is Australia’s national gemstone, and today the vast majority of the world’s precious opals are sourced here. These beautiful gems are unique for their remarkable play of colour, produced by the diffraction and interference of light by the microscopic spheres of silica that form the structure of the opal.
The formation of Australian opals began tens of millions of years ago, when much of central Australia was a vast, shallow inland sea. Fine sands rich in the compound silica were deposited along its shorelines. As the sea receded, the Great Artesian Basin was formed below ground and today’s deserts were slowly created. Through millions of years of weathering, a silica-rich solution seeped along faults and joints in the earth, filling in cracks and voids. This gel eventually hardened to form opal. Sometimes fossil remains such as dinosaur bones, shells and plants were replaced with opal, their shapes still apparent.
The opals depicted in this series of stamps show the wide range of opal types found in Australia. They originated in various important opal-mining sites of Queensland, South Australia and New South Wales, and are now among the treasures of museum collections across the country.
Technical specifications
- Issue date
- 24 June 2025
- Issue withdrawal date
- 31 December 2029
- Denomination
- 1 × $3.50, 1 × $4.35, 1 × $4.80
- Stamp & product design
- Sharon Rodziewicz, Australia Post Design Studio
- Paper: gummed
- Tullis Russell 104gsm Red Phosphor/Blue PVA Stamp Paper
- Printer: gummed
- RA
- Printing process
- Offset lithography
- Stamp size (mm)
- 26 x 37.5
- Minisheet size (mm)
- 170 x 80
- Perforations
- 14.6 x 13.86
- Sheet layout
- Module of 50 (2 x 25)
- FDI postmark
- Andamooka SA 5722
- FDI withdrawal date
- 23 July 2025
$3.50 (International)
Crystal Opal from Andamooka, South Australia
The opal featured is from the Australian Museum in Sydney, photograph by Carl Bento. It was unearthed at Andamooka, on the traditional lands of the Kokatha people, where opal mining began in the 1930s.
$4.35 (International)
Dark Crystal Opal from Lightning Ridge, New South Wales
This Dark Crystal Opal was found by a member of a film crew who picked it up from a pile of dirt while filming in Lightning Ridge. It is now in the Brisbane Opal Museum. Photograph by Valentine McDonald.
$4.80 (International)
Yowah Nut Opal from Yowah, Queensland
Yowah Nuts take their name from the only place in the world where they occur: Yowah in south-west Queensland. These opals form inside ironstone ‘nuts’ which, when split open, can reveal opals with flashes of brilliant colour.The Yowah Nut featured is from the Brisbane Opal Museum, photograph by Valentine McDonald.
