Common sizes for many of the opal cabochons set in jewelry are 6×4, 7×5, and 8×6 mm. The Fire of Australia, a large uncut opal, weighs 998 grams or just under 5,000 carats. South Australia is one of ...

Jorge Tamayo Carrillo (Opalos & Artesanias Mexicanas, Magdalena, Mexico) outlined current production of fire opal at his family ... rhyolite matrix with gemmy opal portions—is fabricated by hand into ...