The Fire of Australia, discovered by the Bertram family in 1946, is the most valuable piece of rough light opal of its size in the world, weighing approximately 5,000 carats. Photo: By Ray Bartram and courtesy of the Bartram family.

The Fire of Australia, discovered by the Bertram family in 1946, is the most valuable piece of rough light opal of its size in the world, weighing approximately 5,000 carats. Photo: By Ray Bartram and courtesy of the Bartram family.

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