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1-530: The Andamooka Opal is a famous opal which was presented to Queen Elizabeth II in 1954 on the occasion of her first visit to South Australia . The opal was mined in Andamooka in 1949. The opal was cut and polished by John Altmann to a weight of 203 carats (40.6 g). It displays a magnificent array of reds, blues, and greens and was set with diamonds into an 18 karat (75%) palladium necklet. Other notable individual opals: This gemology article