how expensive is an opal
Most Expensive Opal in the World. Olympic Australis, valued at $2 million dollars (2.5 million Australian dollars), is the world's most valuable gem opal. The gemstone is also the world's largest with a weight of 17,000 carats (3450 grams) a length of 11 inches (280 mm), a height of 4Â¾ inches (120 mm) and a width of 4Â½ inches (115 mm). Yet what truly made Olympic Australis extraordinary was its 99% real gem opal of even color, with only 1% soil adhered to it. In honor of the Olympic games being held during its discovery in 1956, the miner who found it at Eight Mile opal field in Coober Pedy, South Australia named the gem Olympic Australis.